Ola Svensson | University of Borås (original) (raw)

Papers by Ola Svensson

Research paper thumbnail of The importance of sperm competition risk and nest appearance for male behavior and female choice in the sand goby, Pomatoschistus minutus

Behavioral Ecology, Sep 29, 2005

Research paper thumbnail of Sand Goby—An Ecologically Relevant Species for Behavioural Ecotoxicology

Research paper thumbnail of Sperm adaptation in relation to salinity in three goby species

Journal of Fish Biology, May 7, 2021

Research paper thumbnail of Invader at the edge — Genomic origins and physiological differences of round gobies across a steep urban salinity gradient

Evolutionary Applications

Species invasions are a global problem of increasing concern, especially in highly connected aqua... more Species invasions are a global problem of increasing concern, especially in highly connected aquatic environments. Despite this, salinity conditions can pose physiological barriers to their spread, and understanding them is important for management. In Scandinavia's largest cargo port, the invasive round goby (Neogobius melanostomus) is established across a steep salinity gradient. We used 12,937 SNPs to identify the genetic origin and diversity of three sites along the salinity gradient and round goby from western, central and northern Baltic Sea, as well as north European rivers. Fish from two sites from the extreme ends of the gradient were also acclimated to freshwater and seawater, and tested for respiratory and osmoregulatory physiology. Fish from the high‐salinity environment in the outer port showed higher genetic diversity, and closer relatedness to the other regions, compared to fish from lower salinity upstream the river. Fish from the high‐salinity site also had high...

Research paper thumbnail of Acoustic and visual courtship traits in two sympatric marine Gobiidae species – Pomatoschistus microps and Pomatoschistus minutus

Environmental Biology of Fishes, Nov 16, 2016

Research paper thumbnail of Supplementary material from "The genetics of mate preferences in hybrids between two young and sympatric Lake Victoria cichlid species

The genetic architecture of mate preferences is likely to affect significant evolutionary process... more The genetic architecture of mate preferences is likely to affect significant evolutionary processes, including speciation and hybridization. Here, we investigate laboratory hybrids between a pair of sympatric Lake Victoria cichlid fish species that appear to have recently evolved from a hybrid population between similar predecessor species. The species demonstrate strong assortative mating in the laboratory, associated with divergent male breeding coloration (red dorsum versus blue). We show in a common garden experiment, using DNA-based paternity testing, that the strong female mate preferences among males of the two species are fully recovered in a large fraction of their F2 hybrid generation. Individual hybrid females often demonstrated consistent preferences in multiple mate choice trials (more than or equal to five) across a year or more. This result suggests that female mate preference is influenced by relatively few major genes or genomic regions. These preferences were not changed by experience of a successful spawning event with a male of the non-preferred species in a no-choice single-male trial. We found no evidence for imprinting in the F2 hybrids, although the F1 hybrid females may have been imprinted on their mothers. We discuss this nearly Mendelian inheritance of consistent innate mate preferences in the context of speciation theory.

Research paper thumbnail of Parental behaviour in relation to the occurrence of sneaking in the common goby

Animal Behaviour, Jul 1, 1998

Research paper thumbnail of Table S4. Raw data and paternal analyses

Table S4 includes microsatellite raw data of the offspring of the F2 females (q1-35 and 1-286), t... more Table S4 includes microsatellite raw data of the offspring of the F2 females (q1-35 and 1-286), the wild type females (p and n) and the F1 hybrid females (pn and np), as well as the paternity analyses. ID (Blank): The ID of the female used in Table S1-2, Brood No: The numer of the brood, Prefix: The prefix in the PIT-tag number, Suffix: The suffix in the PIT-tag number, SL (mm): Standard length (mm), TL (mm): Total lenght (mm), Weight (g), No fry: Number of fry in the brood, Date stripped, No broods, Experimental round: Experimental round in Table S1-2, (Blank), Mother: Result of maternal analyses (same as ID if left blank), Father: Result of the paternity analyses, Ppun7a: Microsatellite lengt in base pairs (bp), Ppun7b: Microsatellite lengt in base pairs (bp), Ppun5a: Microsatellite lengt in base pairs (bp), Ppun5b: Microsatellite lengt in base pairs (bp), Ppun21a: Microsatellite lengt in base pairs (bp), Ppun21b: Microsatellite lengt in base pairs (bp), Ppun17a: Microsatellite lengt in base pairs (bp), Ppun17b: Microsatellite lengt in base pairs (bp), Ppun32a: Microsatellite lengt in base pairs (bp), Ppun32b: Microsatellite lengt in base pairs (bp)

Research paper thumbnail of Offspring recognition and the influence of clutch size on nest fostering among male sand gobies, Pomatoschistus minutus

Behavioral Ecology and Sociobiology, Mar 25, 2010

Research paper thumbnail of Male mating success in relation to food availability in the common goby

Journal of Fish Biology, May 1, 2003

Research paper thumbnail of Continuous but not intermittent noise has a negative impact on mating success in a marine fish with paternal care

Scientific Reports, Apr 2, 2019

Research paper thumbnail of Courtship Sounds Advertise Species Identity and Male Quality in Sympatric Pomatoschistus spp. Gobies

Research paper thumbnail of Male acoustic display in the sand goby – Essential cue in female choice, but unaffected by supplemental feeding

Journal of Experimental Marine Biology and Ecology

Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey... more Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey information about body condition. Here we experimentally altered body condition of sand goby (Pomatoschistus minutus) males to examine effects on acoustic and visual courtship and subsequent spawning decisions. Over two weeks, males fed in excess were fed daily, whereas food-deprived males were fed once a week. Females only spawned with males that produced courtship sound. However, there were no treatment effects on the occurrence of spawning and males fed in excess did not invest more in visual or acoustic courtship than food-deprived males. That said, males fed in excess built more well-covered nests, with more sand piled on top, compared to fooddeprived males. Male condition measured as lipid content differed significantly between treatments. However, only males fed in excess differed in lipid content from wild caught males, indicating that in nature, males are of similar condition to males in the low condition treatment group. Apart from the importance of courtship sound, the only male or female behaviour predicting reproductive success was if male displayed in the nest opening. Males often produce courtship sounds together with a visual display in this position. A female dark-eye display did not associate with reproductive success which, together with previous results, suggest a non-ornamental function of this trait. We conclude that male courtship sounds appear to be crucial in female mate choice, but the information content of the courtship sounds and how it relates to male condition remains elusive.

Research paper thumbnail of Electronic supplementary material, figures S1-4 from The genetics of mate preferences in hybrids between two young and sympatric Lake Victoria cichlid species

Research paper thumbnail of Male acoustic display in the sand goby -Essential cue in female choice, but unaffected by supplemental feeding

Journal of Experimental Marine Biology and Ecology, 2022

Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey... more Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey information about body condition. Here we experimentally altered body condition of sand goby (Pomatoschistus minutus) males to examine effects on acoustic and visual courtship and subsequent spawning decisions. Over two weeks, males fed in excess were fed daily, whereas food-deprived males were fed once a week. Females only spawned with males that produced courtship sound. However, there were no treatment effects on the occurrence of spawning and males fed in excess did not invest more in visual or acoustic courtship than food-deprived males. That said, males fed in excess built more well-covered nests, with more sand piled on top, compared to fooddeprived males. Male condition measured as lipid content differed significantly between treatments. However, only males fed in excess differed in lipid content from wild caught males, indicating that in nature, males are of similar condition to males in the low condition treatment group. Apart from the importance of courtship sound, the only male or female behaviour predicting reproductive success was if male displayed in the nest opening. Males often produce courtship sounds together with a visual display in this position. A female dark-eye display did not associate with reproductive success which, together with previous results, suggest a non-ornamental function of this trait. We conclude that male courtship sounds appear to be crucial in female mate choice, but the information content of the courtship sounds and how it relates to male condition remains elusive.

Research paper thumbnail of Molecular, behavioural and morphological comparisons of sperm adaptations in a fish with alternative reproductive tactics

Evolutionary Applications, 2022

In species with alternative reproductive tactics, there is much empirical support that parasitica... more In species with alternative reproductive tactics, there is much empirical support that parasitically spawning males have larger testes and greater sperm numbers as an evolved response to a higher degree of sperm competition, but support for higher sperm performance (motility, longevity and speed) by such males is inconsistent. We used the sand goby (Pomatoschistus minutus) to test whether sperm performance differed between breeding-coloured males (small testes, large mucus-filled sperm-duct glands; build nests lined with sperm-containing mucus, provide care) and parasitic sneaker-morph males (no breeding colouration, large testes, rudimentary sperm-duct glands; no nest, no care). We compared motility (per cent motile sperm), velocity, longevity of sperm, gene expression of testes and sperm morphometrics between the two morphs. We also tested if sperm-duct gland contents affected sperm performance. We found a clear difference in gene expression of testes between the male morphs with 109 transcripts differentially expressed between the morphs. Notably, several mucin genes were upregulated in breeding-coloured males and two ATP-related genes were upregulated in sneaker-morph males. There was a partial evidence of higher sperm velocity in sneaker-morph males, but no difference in sperm motility. Presence of sperm-duct gland contents significantly increased sperm velocity, and nonsignificantly tended to increase sperm motility, but equally so for the two morphs. The sand goby has remarkably long-lived sperm, with only small or no decline in motility and velocity over time (5 min vs. 22 h), but again, this was equally true for both morphs. Sperm length (head, flagella, total and flagella-to-head ratio) did not differ between morphs and did not correlate with sperm velocity for either morph. Thus, other than a clear difference in testes gene expression, we found only modest differences between the two male morphs, confirming previous findings that increased sperm performance as an adaptation to sperm competition is not a primary target of evolution.

Research paper thumbnail of Invader at the edge -Genomic origins and physiological differences of round gobies across a steep urban salinity gradient

Evolutionary Applications, 2022

Species invasions are a global problem of increasing concern, especially in highly connected aqua... more Species invasions are a global problem of increasing concern, especially in highly connected aquatic environments. Despite this, salinity conditions can pose physiological barriers to their spread, and understanding them is important for management. In Scandinavia's largest cargo port, the invasive round goby (Neogobius melanostomus) is established across a steep salinity gradient. We used 12,937 SNPs to identify the genetic origin and diversity of three sites along the salinity gradient and round goby from western, central and northern Baltic Sea, as well as north European rivers. Fish from two sites from the extreme ends of the gradient were also acclimated to freshwater and seawater, and tested for respiratory and osmoregulatory physiology. Fish from the high-salinity environment in the outer port showed higher genetic diversity, and closer relatedness to the other regions, compared to fish from lower salinity upstream the river. Fish from the high-salinity site also had higher maximum metabolic rate, fewer blood cells and lower blood Ca2+. Despite these genotypic and phenotypic differences, salinity acclimation affected fish from both sites in the same way: seawater increased the blood osmolality and Na+ levels, and freshwater increased the levels of the stress hormone cortisol. Our results show genotypic and phenotypic differences over short spatial scales across this steep salinity gradient. These patterns of the physiologically robust round goby are likely driven by multiple introductions into the high-salinity site, and a process of sorting, likely based on behaviour or selection, along the gradient. This euryhaline fish risks spreading from this area, and seascape genomics and phenotypic characterization can inform management strategies even within an area as small as a coastal harbour inlet.

Research paper thumbnail of How sexual and natural selection interact and shape the evolution of nests and nesting behaviour in fishes

Philosophical Transactions of the Royal Society B, 2023

Among ray-finned fishes that provide parental care, many spawn in constructed nests, ranging from... more Among ray-finned fishes that provide parental care, many spawn in constructed nests, ranging from bowls, burrows and ridges to nests made of algae or bubbles. Because a nest by definition is a construction that enhances the nest-builder's fitness by helping it meet the needs of the developing offspring, nest-building behaviour is naturally selected, as is a preference for spawning with mates that provide well-built nests. However, nest-building behaviour can also be sexually selected, when nest traits increase mating success, protect against sperm competition or nest take-overs by conspecifics. Here, we offer a systematic review, with examples of how competition for sites and location of fish nests relates to sexual selection. We examine direct and indirect benefits of mate choice linked to nest traits, and different types of nests, from a sexual selection perspective. Nest-related behaviours are often under both natural and sexual selection, and we disentangle examples where that is the case, with special attention to females. We highlight some taxa in which nest building is likely to be sexually selected, but lack of research has left them uninvestigated. Some of them are established aquarium species, making them particularly amenable for future research. Finally, we compare with arthropods, amphibians and birds.

Research paper thumbnail of Increased noise levels cause behavioural and distributional changes in Atlantic cod and saithe in a large public aquarium-A case study

Aquaculture, Fish & Fisheries, 2023

Investigating the effects of underwater noise on aquatic animals is a research field that is rece... more Investigating the effects of underwater noise on aquatic animals is a research field that is receiving rapidly increasing attention. Despite this, surprisingly few studies have addressed the potential impacts of noise in a marine animal husbandry setting. In this regard, the behaviour of fish in public aquariums can be used as an indicator of well-being, and noise is known to cause behavioural changes. This case study investigates the behaviour of cod (Gadus morhua) and saithe (Pollachius virens) in a large public aquarium when exposed to increased noise levels originating from an aquarium renovation carried out by construction divers. Swimming behaviour, group formation and vertical distribution, along with yawning and scratching frequencies of the fish, were analysed from video recordings made before, during and after the exposure to increased noise levels. The same parameters were also analysed to evaluate potential effects of the presence of divers when not making renovation noise, compared to fish behaviour prior to the renovation. There was a slight change in the depth distribution of both species and a decrease in the number of scratches in cod due to the presence of divers that were not making renovation noise. In the presence of construction noises in the tank, however, both cod and saithe showed a wider array of behavioural changes, including increased swimming speed, changes in depth distribution and increased yawning frequencies. The results from this case study demonstrate that an underwater renovation with increased noise levels impacts fish behaviour and suggests that underwater noise should be considered during the management of aquatic environments, including public aquaria.

Research paper thumbnail of Continuous but not intermittent noise has a negative impact on mating success in a marine fish with paternal care

Scientific Reports, 2019

Anthropogenic underwater noise is a global pollutant of increasing concern but its impact on repr... more Anthropogenic underwater noise is a global pollutant of increasing concern but its impact on reproduction in fish is largely unknown. Hence, a better understanding of its consequences for this important link to fitness is crucial. Working in aquaria, we experimentally tested the impact of broadband noise exposure (added either continuously or intermittently), compared to a control, on the behaviour and reproductive success of the common goby (Pomatoschistus microps), a vocal fish with exclusive paternal care. Compared to the intermittent noise and control treatments, the continuous noise treatment increased latency to female nest inspection and spawning and decreased spawning probability. In contrast, many other female and male pre-spawning behaviours, and female ventilation rate (proxies for stress levels) did not differ among treatments. Therefore, it is likely that female spawning decisions were delayed by a reduced ability to assess male acoustic signals, rather than due to stre...

Research paper thumbnail of The importance of sperm competition risk and nest appearance for male behavior and female choice in the sand goby, Pomatoschistus minutus

Behavioral Ecology, Sep 29, 2005

Research paper thumbnail of Sand Goby—An Ecologically Relevant Species for Behavioural Ecotoxicology

Research paper thumbnail of Sperm adaptation in relation to salinity in three goby species

Journal of Fish Biology, May 7, 2021

Research paper thumbnail of Invader at the edge — Genomic origins and physiological differences of round gobies across a steep urban salinity gradient

Evolutionary Applications

Species invasions are a global problem of increasing concern, especially in highly connected aqua... more Species invasions are a global problem of increasing concern, especially in highly connected aquatic environments. Despite this, salinity conditions can pose physiological barriers to their spread, and understanding them is important for management. In Scandinavia's largest cargo port, the invasive round goby (Neogobius melanostomus) is established across a steep salinity gradient. We used 12,937 SNPs to identify the genetic origin and diversity of three sites along the salinity gradient and round goby from western, central and northern Baltic Sea, as well as north European rivers. Fish from two sites from the extreme ends of the gradient were also acclimated to freshwater and seawater, and tested for respiratory and osmoregulatory physiology. Fish from the high‐salinity environment in the outer port showed higher genetic diversity, and closer relatedness to the other regions, compared to fish from lower salinity upstream the river. Fish from the high‐salinity site also had high...

Research paper thumbnail of Acoustic and visual courtship traits in two sympatric marine Gobiidae species – Pomatoschistus microps and Pomatoschistus minutus

Environmental Biology of Fishes, Nov 16, 2016

Research paper thumbnail of Supplementary material from "The genetics of mate preferences in hybrids between two young and sympatric Lake Victoria cichlid species

The genetic architecture of mate preferences is likely to affect significant evolutionary process... more The genetic architecture of mate preferences is likely to affect significant evolutionary processes, including speciation and hybridization. Here, we investigate laboratory hybrids between a pair of sympatric Lake Victoria cichlid fish species that appear to have recently evolved from a hybrid population between similar predecessor species. The species demonstrate strong assortative mating in the laboratory, associated with divergent male breeding coloration (red dorsum versus blue). We show in a common garden experiment, using DNA-based paternity testing, that the strong female mate preferences among males of the two species are fully recovered in a large fraction of their F2 hybrid generation. Individual hybrid females often demonstrated consistent preferences in multiple mate choice trials (more than or equal to five) across a year or more. This result suggests that female mate preference is influenced by relatively few major genes or genomic regions. These preferences were not changed by experience of a successful spawning event with a male of the non-preferred species in a no-choice single-male trial. We found no evidence for imprinting in the F2 hybrids, although the F1 hybrid females may have been imprinted on their mothers. We discuss this nearly Mendelian inheritance of consistent innate mate preferences in the context of speciation theory.

Research paper thumbnail of Parental behaviour in relation to the occurrence of sneaking in the common goby

Animal Behaviour, Jul 1, 1998

Research paper thumbnail of Table S4. Raw data and paternal analyses

Table S4 includes microsatellite raw data of the offspring of the F2 females (q1-35 and 1-286), t... more Table S4 includes microsatellite raw data of the offspring of the F2 females (q1-35 and 1-286), the wild type females (p and n) and the F1 hybrid females (pn and np), as well as the paternity analyses. ID (Blank): The ID of the female used in Table S1-2, Brood No: The numer of the brood, Prefix: The prefix in the PIT-tag number, Suffix: The suffix in the PIT-tag number, SL (mm): Standard length (mm), TL (mm): Total lenght (mm), Weight (g), No fry: Number of fry in the brood, Date stripped, No broods, Experimental round: Experimental round in Table S1-2, (Blank), Mother: Result of maternal analyses (same as ID if left blank), Father: Result of the paternity analyses, Ppun7a: Microsatellite lengt in base pairs (bp), Ppun7b: Microsatellite lengt in base pairs (bp), Ppun5a: Microsatellite lengt in base pairs (bp), Ppun5b: Microsatellite lengt in base pairs (bp), Ppun21a: Microsatellite lengt in base pairs (bp), Ppun21b: Microsatellite lengt in base pairs (bp), Ppun17a: Microsatellite lengt in base pairs (bp), Ppun17b: Microsatellite lengt in base pairs (bp), Ppun32a: Microsatellite lengt in base pairs (bp), Ppun32b: Microsatellite lengt in base pairs (bp)

Research paper thumbnail of Offspring recognition and the influence of clutch size on nest fostering among male sand gobies, Pomatoschistus minutus

Behavioral Ecology and Sociobiology, Mar 25, 2010

Research paper thumbnail of Male mating success in relation to food availability in the common goby

Journal of Fish Biology, May 1, 2003

Research paper thumbnail of Continuous but not intermittent noise has a negative impact on mating success in a marine fish with paternal care

Scientific Reports, Apr 2, 2019

Research paper thumbnail of Courtship Sounds Advertise Species Identity and Male Quality in Sympatric Pomatoschistus spp. Gobies

Research paper thumbnail of Male acoustic display in the sand goby – Essential cue in female choice, but unaffected by supplemental feeding

Journal of Experimental Marine Biology and Ecology

Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey... more Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey information about body condition. Here we experimentally altered body condition of sand goby (Pomatoschistus minutus) males to examine effects on acoustic and visual courtship and subsequent spawning decisions. Over two weeks, males fed in excess were fed daily, whereas food-deprived males were fed once a week. Females only spawned with males that produced courtship sound. However, there were no treatment effects on the occurrence of spawning and males fed in excess did not invest more in visual or acoustic courtship than food-deprived males. That said, males fed in excess built more well-covered nests, with more sand piled on top, compared to fooddeprived males. Male condition measured as lipid content differed significantly between treatments. However, only males fed in excess differed in lipid content from wild caught males, indicating that in nature, males are of similar condition to males in the low condition treatment group. Apart from the importance of courtship sound, the only male or female behaviour predicting reproductive success was if male displayed in the nest opening. Males often produce courtship sounds together with a visual display in this position. A female dark-eye display did not associate with reproductive success which, together with previous results, suggest a non-ornamental function of this trait. We conclude that male courtship sounds appear to be crucial in female mate choice, but the information content of the courtship sounds and how it relates to male condition remains elusive.

Research paper thumbnail of Electronic supplementary material, figures S1-4 from The genetics of mate preferences in hybrids between two young and sympatric Lake Victoria cichlid species

Research paper thumbnail of Male acoustic display in the sand goby -Essential cue in female choice, but unaffected by supplemental feeding

Journal of Experimental Marine Biology and Ecology, 2022

Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey... more Many teleost fishes use acoustic and visual signalling during courtship. Such displays may convey information about body condition. Here we experimentally altered body condition of sand goby (Pomatoschistus minutus) males to examine effects on acoustic and visual courtship and subsequent spawning decisions. Over two weeks, males fed in excess were fed daily, whereas food-deprived males were fed once a week. Females only spawned with males that produced courtship sound. However, there were no treatment effects on the occurrence of spawning and males fed in excess did not invest more in visual or acoustic courtship than food-deprived males. That said, males fed in excess built more well-covered nests, with more sand piled on top, compared to fooddeprived males. Male condition measured as lipid content differed significantly between treatments. However, only males fed in excess differed in lipid content from wild caught males, indicating that in nature, males are of similar condition to males in the low condition treatment group. Apart from the importance of courtship sound, the only male or female behaviour predicting reproductive success was if male displayed in the nest opening. Males often produce courtship sounds together with a visual display in this position. A female dark-eye display did not associate with reproductive success which, together with previous results, suggest a non-ornamental function of this trait. We conclude that male courtship sounds appear to be crucial in female mate choice, but the information content of the courtship sounds and how it relates to male condition remains elusive.

Research paper thumbnail of Molecular, behavioural and morphological comparisons of sperm adaptations in a fish with alternative reproductive tactics

Evolutionary Applications, 2022

In species with alternative reproductive tactics, there is much empirical support that parasitica... more In species with alternative reproductive tactics, there is much empirical support that parasitically spawning males have larger testes and greater sperm numbers as an evolved response to a higher degree of sperm competition, but support for higher sperm performance (motility, longevity and speed) by such males is inconsistent. We used the sand goby (Pomatoschistus minutus) to test whether sperm performance differed between breeding-coloured males (small testes, large mucus-filled sperm-duct glands; build nests lined with sperm-containing mucus, provide care) and parasitic sneaker-morph males (no breeding colouration, large testes, rudimentary sperm-duct glands; no nest, no care). We compared motility (per cent motile sperm), velocity, longevity of sperm, gene expression of testes and sperm morphometrics between the two morphs. We also tested if sperm-duct gland contents affected sperm performance. We found a clear difference in gene expression of testes between the male morphs with 109 transcripts differentially expressed between the morphs. Notably, several mucin genes were upregulated in breeding-coloured males and two ATP-related genes were upregulated in sneaker-morph males. There was a partial evidence of higher sperm velocity in sneaker-morph males, but no difference in sperm motility. Presence of sperm-duct gland contents significantly increased sperm velocity, and nonsignificantly tended to increase sperm motility, but equally so for the two morphs. The sand goby has remarkably long-lived sperm, with only small or no decline in motility and velocity over time (5 min vs. 22 h), but again, this was equally true for both morphs. Sperm length (head, flagella, total and flagella-to-head ratio) did not differ between morphs and did not correlate with sperm velocity for either morph. Thus, other than a clear difference in testes gene expression, we found only modest differences between the two male morphs, confirming previous findings that increased sperm performance as an adaptation to sperm competition is not a primary target of evolution.

Research paper thumbnail of Invader at the edge -Genomic origins and physiological differences of round gobies across a steep urban salinity gradient

Evolutionary Applications, 2022

Species invasions are a global problem of increasing concern, especially in highly connected aqua... more Species invasions are a global problem of increasing concern, especially in highly connected aquatic environments. Despite this, salinity conditions can pose physiological barriers to their spread, and understanding them is important for management. In Scandinavia's largest cargo port, the invasive round goby (Neogobius melanostomus) is established across a steep salinity gradient. We used 12,937 SNPs to identify the genetic origin and diversity of three sites along the salinity gradient and round goby from western, central and northern Baltic Sea, as well as north European rivers. Fish from two sites from the extreme ends of the gradient were also acclimated to freshwater and seawater, and tested for respiratory and osmoregulatory physiology. Fish from the high-salinity environment in the outer port showed higher genetic diversity, and closer relatedness to the other regions, compared to fish from lower salinity upstream the river. Fish from the high-salinity site also had higher maximum metabolic rate, fewer blood cells and lower blood Ca2+. Despite these genotypic and phenotypic differences, salinity acclimation affected fish from both sites in the same way: seawater increased the blood osmolality and Na+ levels, and freshwater increased the levels of the stress hormone cortisol. Our results show genotypic and phenotypic differences over short spatial scales across this steep salinity gradient. These patterns of the physiologically robust round goby are likely driven by multiple introductions into the high-salinity site, and a process of sorting, likely based on behaviour or selection, along the gradient. This euryhaline fish risks spreading from this area, and seascape genomics and phenotypic characterization can inform management strategies even within an area as small as a coastal harbour inlet.

Research paper thumbnail of How sexual and natural selection interact and shape the evolution of nests and nesting behaviour in fishes

Philosophical Transactions of the Royal Society B, 2023

Among ray-finned fishes that provide parental care, many spawn in constructed nests, ranging from... more Among ray-finned fishes that provide parental care, many spawn in constructed nests, ranging from bowls, burrows and ridges to nests made of algae or bubbles. Because a nest by definition is a construction that enhances the nest-builder's fitness by helping it meet the needs of the developing offspring, nest-building behaviour is naturally selected, as is a preference for spawning with mates that provide well-built nests. However, nest-building behaviour can also be sexually selected, when nest traits increase mating success, protect against sperm competition or nest take-overs by conspecifics. Here, we offer a systematic review, with examples of how competition for sites and location of fish nests relates to sexual selection. We examine direct and indirect benefits of mate choice linked to nest traits, and different types of nests, from a sexual selection perspective. Nest-related behaviours are often under both natural and sexual selection, and we disentangle examples where that is the case, with special attention to females. We highlight some taxa in which nest building is likely to be sexually selected, but lack of research has left them uninvestigated. Some of them are established aquarium species, making them particularly amenable for future research. Finally, we compare with arthropods, amphibians and birds.

Research paper thumbnail of Increased noise levels cause behavioural and distributional changes in Atlantic cod and saithe in a large public aquarium-A case study

Aquaculture, Fish & Fisheries, 2023

Investigating the effects of underwater noise on aquatic animals is a research field that is rece... more Investigating the effects of underwater noise on aquatic animals is a research field that is receiving rapidly increasing attention. Despite this, surprisingly few studies have addressed the potential impacts of noise in a marine animal husbandry setting. In this regard, the behaviour of fish in public aquariums can be used as an indicator of well-being, and noise is known to cause behavioural changes. This case study investigates the behaviour of cod (Gadus morhua) and saithe (Pollachius virens) in a large public aquarium when exposed to increased noise levels originating from an aquarium renovation carried out by construction divers. Swimming behaviour, group formation and vertical distribution, along with yawning and scratching frequencies of the fish, were analysed from video recordings made before, during and after the exposure to increased noise levels. The same parameters were also analysed to evaluate potential effects of the presence of divers when not making renovation noise, compared to fish behaviour prior to the renovation. There was a slight change in the depth distribution of both species and a decrease in the number of scratches in cod due to the presence of divers that were not making renovation noise. In the presence of construction noises in the tank, however, both cod and saithe showed a wider array of behavioural changes, including increased swimming speed, changes in depth distribution and increased yawning frequencies. The results from this case study demonstrate that an underwater renovation with increased noise levels impacts fish behaviour and suggests that underwater noise should be considered during the management of aquatic environments, including public aquaria.

Research paper thumbnail of Continuous but not intermittent noise has a negative impact on mating success in a marine fish with paternal care

Scientific Reports, 2019

Anthropogenic underwater noise is a global pollutant of increasing concern but its impact on repr... more Anthropogenic underwater noise is a global pollutant of increasing concern but its impact on reproduction in fish is largely unknown. Hence, a better understanding of its consequences for this important link to fitness is crucial. Working in aquaria, we experimentally tested the impact of broadband noise exposure (added either continuously or intermittently), compared to a control, on the behaviour and reproductive success of the common goby (Pomatoschistus microps), a vocal fish with exclusive paternal care. Compared to the intermittent noise and control treatments, the continuous noise treatment increased latency to female nest inspection and spawning and decreased spawning probability. In contrast, many other female and male pre-spawning behaviours, and female ventilation rate (proxies for stress levels) did not differ among treatments. Therefore, it is likely that female spawning decisions were delayed by a reduced ability to assess male acoustic signals, rather than due to stre...