Reproductive Strategies Research Papers - Academia.edu (original) (raw)

Mammals are the most diverse species on Earth. It is vital to understanding the origin of mammals by using fossil records as evidence. Fossil records that are recently discovered hold a significant information regarding the origin of... more

Mammals are the most diverse species on Earth. It is vital to understanding the origin of mammals by using fossil records as evidence. Fossil records that are recently discovered hold a significant information regarding the origin of mammals. Mammals have different sizes, forms and shapes. These varieties help mammals to demonstrate adaptive behavior in order to survive the environmental and habitat changes. All mammals are interacting with each other. Human, as a species of mammal, domesticates other species. The domestication may impact the intelligence strategy of some mammals. The domestication requires studying the behavior of species related to the physical structure, such as migratory behavior, communication behavior, and sexual behavior. The reproductive system in mammal differs from other species. Mammals have several reproductive strategies that are aligned with the changes in environment and habitat.

As one means to maximize access to females, males of some species are intolerant of other males in social units, resulting in female defense polygyny, a mating system in which one male monopolizes mating access to as many females as he... more

As one means to maximize access to females, males of some species are intolerant of other males in social units, resulting in female defense polygyny, a mating system in which one male monopolizes mating access to as many females as he can for as long as possible. In such a system, the length of a male’s tenure and the number of females he is able to acquire are important predictors of his reproductive success. Hamadryas baboons differ from many other taxa with female defense polygyny in that they acquire and lose females individually, thus patterns of acquisition and loss of females over time are additional factors contributing to a male’s fitness. Here we describe longitudinal patterns of female acquisition and loss over a nine-year period in a group of 250 wild hamadryas baboons. Complete tenures of leader males ranged from 310 to 2160 days (N=13) and results from a survival analysis yielded a median tenure length of 2160 days, or 6 years (N=49). The total number of females acquired, which increased with tenure length, ranged from 1 to 14 and averaged 3.5, and leader males acquired females both opportunistically and via challenging other males. The interval between acquisition of successive females ranged from 0 to 1196 days with a median of 203, and males acquired all of their females less than two years into their tenure. Females from outside of a leader male’s social sphere (clan and band) were acquired relatively later in their tenure compared to females from within a male’s social sphere. Leaders typically lost females gradually during the latter part of their tenure or all (or most) at once, suggesting an inverted U-shaped longitudinal arc of male competitive ability.

Комплексное использование кладистического и семогенетического подходов позволяет получить ответ на вопросы, связанные как с филогенетическими отношениями между представителями группы, так и с филогенезом признаков у этих представителей.... more

Комплексное использование кладистического и семогенетического подходов позволяет получить ответ на вопросы, связанные как с филогенетическими отношениями между представителями группы, так и с филогенезом признаков у этих представителей. Забота о потомстве и другие формы репродуктивного поведения, а также стратегии размножения в целом могут быть объектом семоге-нетического анализа наряду с морфоструктурами sensu stricto. Одной из наиболее высокоспециа-лизированных форм родительской заботы у рыб, в том числе у представителей подотряда ползуно-видных и сестринских по отношению к нему групп, является кормление потомства и обеспечение его пищей. С нашей точки зрения, эволюционное происхождение постэмбрионального обеспече-ния потомства кормом у костных рыб характеризуется тремя основными особенностями: 1. Раз-личные формы постэмбрионального обеспечения потомства кормом у рыб имеют конвергентное происхождение. 2. Любая из них реализуется на базе уже существующего признака и поддержива-ется отбором вследствие повышения приспособленности потомства. 3. Основным эволюционным путем возникновения и развития данного феномена является расширение и смена функции. Данная гипотеза обладает эвристической силой, поскольку позволяет прогнозировать наличие обсуждае-мого компонента репродуктивной стратегии на основе выявления адекватных базовых адаптаций. Несмотря на то что родительская забота свойственна большинству ползуновидных, существует несколько видов, у которых забота о потомстве не известна. Виды с такой репродуктивной стра-тегией занимают отнюдь не самое базальное положение на кладограмме, а находятся в окружении рыб, в той или иной форме заботящихся о своей кладке, а порой и выводке. Принцип парсимонии позволяет предположить, что родительская забота является плезиоморфным признаком подотряда Anabantoidei (или отряда Anabantiformes). На наш взгляд, предками современных видов, не забо-тящихся о потомстве и занимающих различное положение в данной филогенетической группе, были проявляющие заботу о потомстве рыбы, репродуктивная стратегия которых претерпела из-менение вследствие r-отбора. Если эта гипотеза верна, отсутствие заботы о потомстве следует рассматривать как случай упрощения репродуктивной стратегии. Высока вероятность того, что репродуктивная стратегия предковых форм включала в себя те или иные формы обеспечения по-томства кормом. Не исключено, что репродуктивная стратегия современных Anabantiformes, якобы не заботящихся о потомстве, включает в себя факультативные формы родительской заботы.

In contrast to other papionin monkeys, hamadryas baboons are characterized by female-biased dispersal. Given that hamadryas females do not disperse voluntarily, one mechanism for female transfer between bands is thought to be abductions... more

In contrast to other papionin monkeys, hamadryas baboons are characterized by female-biased dispersal. Given that hamadryas females do not disperse voluntarily, one mechanism for female transfer between bands is thought to be abductions during aggressive intergroup conflict. To date, however, no successful abductions have been witnessed. We describe three abduction events at the Filoha field site in Ethiopia, two interband and one intraband, in which the abductors successfully separated a female from her leader male for several minutes or hours. In each case, the original leader male located the abductor and retrieved the female, even if it involved entering the social sphere of another band. These observations suggest that a hamadryas leader male will risk injury and loss of additional females in his attempt to retrieve a female from an abductor unless the abductor has openly challenged the leader for possession of his female and physically defeated him.

Clado- and semogenetic approaches, when used in concert, make it possible to resolve questions concerning the phylogenetic relationships between group representatives, as well as the phylogenesis of those representatives’ characters.... more

Clado- and semogenetic approaches, when used in concert, make it possible to resolve questions concerning the phylogenetic relationships between group representatives, as well as the phylogenesis of those representatives’ characters. Parental care patterns and other forms of reproductive behavior, along with the reproductive strategy as a whole, can be the subject of semogenetic analysis to no less an extent than morphological structures sensu stricto. One highly specialized form of parental care in fish, including representatives of the suborder of labyrinth fishes and their sister groups, appears to be parental food provisioning. In our view, the evolutionary origin of postembryonic brood provisioning in bony fishes is characterized by three main features: (1) in fish, different forms of postembryonic food provisioning are convergent in their origin; (2) any kind of brood provisioning is realized through exploitation of the already existing character and is maintained by selection due to an enhancement of offspring fitness; (3) the main evolutionary path of the emergence and development of this phenomenon consists in function expansion and replacement. The hypothesis does have heuristic power, since it enables prediction of the presence of the reproductive strategy component in question through the identification of adequate basic adaptations. Although parental care occurs in the majority of anabantoid fishes, there are still several species for which such care is not known. On the cladogram, these species by no means take the basal position but are surrounded by fishes that provide care for their eggs, or even their hatchlings. The parsimony principle leads to the suggestion that parental care is a plesiomorphic character in the suborder Anabantoidei (or in the order Anabantiformes). It seems that the ancestors of present day noncarrying species that take various positions within this phylogenetic group were fishes showing parental care. Their reproductive strategy later changed as a result of r selection. If this hypothesis is correct, the absence of parental care should be considered a case of reproductive strategy degradation. It is quite probable that parental food provisioning was a component of the ancestral reproductive strategies. It is also possible that the reproductive strategy of present-day anabantoids that supposedly do not care for their offspring actually includes some optional forms of parental care.

OBJECTIVES: One-male social systems are usually characterized by polygyny and reproductive exclusion by a single resident male. Sometimes, however, secondary males join these groups, and this may carry fitness costs and/or benefits to the... more

OBJECTIVES: One-male social systems are usually characterized by polygyny and reproductive exclusion by a single resident male. Sometimes, however, secondary males join these groups, and this may carry fitness costs and/or benefits to the resident male. In hamadryas baboons (Papio hamadryas hamadryas), which live in one-male units (OMUs) with female defense polygyny within a multi-level social system, secondary “follower” males often reside in OMUs. Our aim here is to examine possible benefits of these secondary males to hamadryas resident males.
MATERIALS AND METHODS: Using 6 years of data from 65 OMUs in a band of wild hamadryas baboons in Ethiopia, we compared demographic and reproductive parameters of OMUs with and without secondary “follower” males to assess whether their presence conferred any reproductive benefits to resident “leader” males.
RESULTS: Leaders with followers had tenure lengths almost twice as long, acquired more than twice as many females, retained females longer, and had three times as many infants during their tenure compared to leaders without followers. DISCUSSION: Hamadryas follower males enabled leaders to retain females for longer periods of time—likely through unit defense, social relationships with OMU members, and/ or infant protection. Hamadryas leaders appear to be able to monopolize access to females despite the presence of followers, and as such any enhanced reproduction derived from the presence of followers likely increases the fitness of the leader rather than the follower. Thus the relationship between leaders and followers in hamadryas society appears to be a mutually beneficial one and tolerance of secondary males may be an adaptive reproductive strategy characterizing hamadryas leader males.

This volume brings together current research on the behavior, ecology, reproduction, and life history – and the interrelations among these variables – of baboons of the genus Papio. Baboons, found throughout Africa and into Arabia,... more

This volume brings together current research on the behavior, ecology, reproduction, and life history – and the interrelations among these variables – of baboons of the genus Papio. Baboons, found throughout Africa and into Arabia, represent one of the best-known primate lineages, renowned for their ecological and behavioral flexibility and adaptability. These characteristics are intimately intertwined with features of baboon life history and reproduction. Contributors to this volume, representing several major, long-term research projects from throughout the African continent, explore reproductive behavior and strategies of adult male and female baboons in a variety of ways. In Part I, authors explore various aspects of baboon reproduction and social organization, focusing on issues such as infanticide, mating strategies and investment, hybridization and genetics in examining how adults go about mating and reproducing. In Part II, these aspects of life are juxtaposed with detailed examinations of life history and parental investment. Together, the chapters in this volume explore reproduction and parenting from a variety of angles and motivate research from both the parental and offspring perspectives and at a variety of taxonomic levels. Articulating studies of reproduction with those of life history conveys a richly detailed portrait of life phases with critical evolutionary consequences. These lines of inquiry together forge new ways to investigate the life periods that matter most in evolution.

Arid environments experience a kind of punctuated equilibrium - long periods of dry stasis and low productivity, interrupted by episodic rainfall which spurs reproduction and movement. We review birds' two main strategies, residency and... more

Arid environments experience a kind of punctuated equilibrium - long periods of dry stasis and low productivity, interrupted by episodic rainfall which spurs reproduction and movement. We review birds' two main strategies, residency and nomadism, and the trade-offs faced by individuals in uncertain times. The environmental cues which trigger nomadism are poorly understood, but include distant thunderstorms.

Fundamental reproductive interests dictate that females generally benefit most from mate selectivity and males from mate quantity. This can create conflict between the sexes and result in sexual coercion: male use of aggression to garner... more

Fundamental reproductive interests dictate that females generally benefit most from mate selectivity and males from mate quantity. This can create conflict between the sexes and result in sexual coercion: male use of aggression to garner mating success at a cost to females. Potential fitness costs of sexual coercion, however, can be difficult to measure. Here we demonstrate benefits to males and costs to females of female defense polygyny in wild hamadryas baboons, cercopithecoid primates in which females are coercively transferred among social units by males, restricting both female choice and bonding among female kin. Of all coercive transfers (takeovers) of females with young infants, 67% were followed by infant mortality, which was significantly more likely to occur after takeovers than at other times. As expected, infant mortality decreased time to subsequent conception but lengthened intervals between surviving infants. Following infant survival, whether a female had experienced a takeover after the previous birth was a significant predictor of subsequent interbirth interval, with interbirth intervals of females remaining with the same male between births being significantly shorter than those of females incurring takeovers between births. Together these results reveal that takeovers increase the chance of infant mortality while delaying subsequent conception. Male-driven female defense polygyny in this species is thus costly to females in two ways. These results demonstrate that reproductive strategies benefitting males can evolve despite substantial costs to females. These costs may be mitigated over the long term, however, by female counterstrategies and protective behavior by males.

Hamadryas baboons are known for their complex, multi-level social structure consisting of troops, bands, and one-male units (OMUs) [Kummer, 1968]. Abegglen [1984] observed a 4th level of social structure comprising several OMUs that... more

Hamadryas baboons are known for their complex, multi-level social structure consisting of troops, bands, and one-male units (OMUs) [Kummer, 1968]. Abegglen [1984] observed a 4th level of social structure comprising several OMUs that rested near one another on sleeping cliffs, traveled most closely together during daily foraging, and sometimes traveled as subgroups independently from the rest of the band. Abegglen called these associations “clans” and suggested that they consisted of related males. Here we confirm the existence of clans in a second wild hamadryas population, a band of about 200 baboons at the Filoha site in lowland Ethiopia. During all-day follows from December 1997 through September 1998 and March 2005 through February 2006, data were collected on activity patterns, social interactions, nearest neighbors, band fissions, and takeovers. Association indices were computed for each dyad of leader males, and results of cluster analyses indicated that in each of the 2 observation periods this band comprised 2 large clans ranging in size from 7 to 13 OMUs. All band fissions occurred along clan lines, and most takeovers involved transfer of females within the same clan. Our results support the notion that clans provide an additional level of flexibility to deal with the sparse distribution of resources in hamadryas habitats. The large clan sizes at Filoha may simply be the largest size that the band can split into and still obtain enough food during periods of food scarcity. Our results also suggest that both male and female relationships play a role in the social cohesion of clans and that males exchange females within clans but not between them.

The nested one-male units (OMUs) of the hamadryas baboon are part of a complex social system in which ‘leader’ males achieve near exclusive mating access by forcibly herding females into permanent consortships. Within this multi-level... more

The nested one-male units (OMUs) of the hamadryas baboon are part of a complex social system in which ‘leader’ males achieve near exclusive mating access by forcibly herding females into permanent consortships. Within this multi-level social system (troops, bands, clans and OMUs) are two types of pre-reproductive males – the follower and solitary male – whose different trajectories converge on the leader role. Here we compare OMU formation strategies of followers, who associate with a particular OMU and may have social access to females, with those of solitary males, who move freely within the band and do not associate regularly with OMUs. Data derive from 42 OMU formations (16 by followers and 26 by solitary males) occurring over eight years in a hamadryas baboon band at the Filoha site in Ethiopia. “Initial units” with sexually immature females (IU strategy) were formed by 44% of followers and 46% of solitary males. The remaining followers took over mature females when their leader was deposed (challenge strategy) or disappeared (opportunistic strategy), or via a seemingly peaceful transfer (inheritance strategy). Solitary males took over mature females from other clans and bands, but mainly from old, injured or vanished leaders within their clan (via both the challenge and opportunistic strategies). Former followers of an OMU were more successful at taking over females from those OMUs than any other category of male. Despite this advantage enjoyed by ex-follower leaders, ex-solitary leaders were equally capable of increasing their OMU size at a comparable rate in their first two years as a leader. These results demonstrate the potential for males to employ both multiple roles (follower versus solitary male) and multiple routes (initial unit, inheritance, challenge, opportunistic) to acquire females and become a leader male in a mating system characterized by female defense polygyny in a competitive arena.

In contrast to other papionin monkeys, hamadryas baboons are characterized by female-biased dispersal. Given that hamadryas females do not disperse voluntarily, one mechanism for female transfer between bands is thought to be abductions... more

In contrast to other papionin monkeys, hamadryas baboons are characterized by female-biased dispersal. Given that hamadryas females do not disperse voluntarily, one mechanism for female transfer between bands is thought to be abductions of females during aggressive intergroup conflict. To date, however, no successful abductions have been witnessed. We describe three abduction events at the Filoha field site in Ethiopia, two inter-band and one intra-band, in which the abductors successfully separated a female from her leader male for several minutes or hours. In each case, the original leader male located the abductor and retrieved the female, even if it involved entering the social sphere of another band. These observations suggest that a hamadryas leader male will risk injury and loss of additional females in his attempt to retrieve a female from an abductor unless the abductor has openly challenged the leader for possession of his female and physically defeated him.

As one means to maximize access to females, males of some species are intolerant of other males in social units, resulting in female defense polygyny, a mating system in which one male monopolizes mating access to as many females as he... more

As one means to maximize access to females, males of some species are intolerant of other males in social units, resulting in female defense polygyny, a mating system in which one male monopolizes mating access to as many females as he can for as long as possible. In such a system, the length of a male's tenure and the number of females he is able to acquire are important predictors of his reproductive success. Hamadryas baboons differ from many other taxa with female defense polygyny in that they acquire and lose females individually, thus patterns of acquisition and loss of females over time are additional factors contributing to a male's fitness. Here, we describe longitudinal patterns of female acquisition and loss over a 9-year period in a group of 250 wild hamadryas baboons. Complete tenures of leader males ranged from 310 to 2,160 days (N = 13) and results from a survival analysis yielded a median tenure length of 2,160 days, or 6 years (N = 49). The total number of f...

Multilevel societies are unique in their ability to facilitate the maintenance of strong and consistent social bonds among some individuals while allowing separation among others, which may be especially important when social and sexual... more

Multilevel societies are unique in their ability to facilitate the maintenance of strong and consistent social bonds among some individuals while allowing separation among others, which may be especially important when social and sexual bonds carry significant and reliable benefits to individuals within social groups. Here we examine the importance of social and sexual bonds in the multilevel society of hamadryas baboons (Papio hamadryas) and apply these principles to social evolution in Plio-Pleistocene hominins. The behavior, adaptations, and socioecology of baboons (Papio spp.) have long been recognized as providing an important comparative sample to elucidate the processes of human evolution, and the social system of hamadryas baboons in particular shares even more similarities with humans than that of other baboons. Here we draw parallels between processes during the evolution of hamadryas social organization and those characterizing late Pliocene or early Pleistocene hominins, most likely Homo erectus. The higher costs of reproduction faced by female Homo erectus, exacerbated by an increased reliance on difficult to acquire, nutrient-dense foods, are commonly thought to have been alleviated by a strengthening of male–female bonds (via male provisioning and the evolution of monogamy) or by the assistance of older, postreproductive females (via grandmothering). We suggest that both of these social arrangements could have been present in Plio-Pleistocene hominins if we assume the development of a multilevel society such as that in hamadryas baboons. The evolution of a multilevel society thus underlies the adaptive potential for the complexity that we see in modern human social organization.

In this paper, we report the first observational evidence of infanticide in wild hamadryas baboons. The study group inhabits the lowlands of the northern Rift Valley in Ethiopia and has been under observation for over 1200 hours, on and... more

In this paper, we report the first observational evidence of infanticide in wild hamadryas baboons. The study group inhabits the lowlands of the northern Rift Valley in Ethiopia and has been under observation for over 1200 hours, on and off, since October 1996. Here we report observations from August and September 2002 of the consequences of two takeovers of known females with black infants. After the first takeover, the respective infant disappeared and was presumed dead within eleven days of the takeover. After the second takeover, the infant incurred repeated severe aggression from its mother’s new leader male and eventually died four days after the takeover. We interpret these findings as support for the sexual selection hypothesis for the occurrence of male infanticide. We suggest that hamadryas leader males usually protect infants born into their units but may withhold this protection – or even directly attack and kill infants – after takeovers.

Unlike most cercopithecines, hamadryas baboons (Papio hamadryas hamadryas) are characterized by female-biased dispersal. To clarify this pattern within the context of their hierarchical social system (comprising one-male units, clans,... more

Unlike most cercopithecines, hamadryas baboons (Papio hamadryas hamadryas) are characterized by female-biased dispersal. To clarify this pattern within the context of their hierarchical social system (comprising one-male units, clans, bands, and troops), we report here seven years of data on female transfers among social units in wild hamadryas baboons in Ethiopia. Female tenure in one-male units (OMUs) ranged from one to 2556 days (N=208) and survival analysis revealed a median tenure length of 1217 days (40 months). Changes in OMU membership consisted almost exclusively of takeovers by males, not voluntary transfer. Of 130 takeovers, 67% occurred within the band and 33% across bands, and, of the 22 takeovers for which we have clan membership data, 77% occurred within, not between, clans. These results reinforce the notion that hamadryas female dispersal is not analogous to sex-biased dispersal in other taxa, because: (1) at least in Ethiopian populations, females do not disperse voluntarily but are transferred, often forcibly, by males; (2) only dispersal between bands will promote gene flow, whereas females are most often rearranged within bands; (3) hamadryas females undergo social dispersal but not usually locational dispersal; and (4) while male hamadryas are far more philopatric than females, they have been observed to disperse. It thus appears that the ancestral baboon pattern of female philopatry and male dispersal has evolved into a system in which neither sex is motivated to disperse, but females are forcibly transferred by males, leading to female-mediated gene flow, and males more rarely disperse to find females.

One-male social systems are usually characterized by polygyny and reproductive exclusion by a single resident male. Sometimes, however, secondary males join these groups, and this may carry fitness costs and/or benefits to the resident... more

One-male social systems are usually characterized by polygyny and reproductive exclusion by a single resident male. Sometimes, however, secondary males join these groups, and this may carry fitness costs and/or benefits to the resident male. In hamadryas baboons (Papio hamadryas hamadryas), which live in one-male units (OMUs) with female defense polygyny within a multi-level social system, secondary "follower" males often reside in OMUs. Our aim here is to examine possible benefits of these secondary males to hamadryas resident males. Using 6 years of data from 65 OMUs in a band of wild hamadryas baboons in Ethiopia, we compared demographic and reproductive parameters of OMUs with and without secondary "follower" males to assess whether their presence conferred any reproductive benefits to resident "leader" males. Leaders with followers had tenure lengths almost twice as long, acquired more than twice as many females, retained females longer, and had three times as many infants during their tenure compared to leaders without followers. Hamadryas follower males enabled leaders to retain females for longer periods of time-likely through unit defense, social relationships with OMU members, and/or infant protection. Hamadryas leaders appear to be able to monopolize access to females despite the presence of followers, and as such any enhanced reproduction derived from the presence of followers likely increases the fitness of the leader rather than the follower. Thus the relationship between leaders and followers in hamadryas society appears to be a mutually beneficial one and tolerance of secondary males may be an adaptive reproductive strategy characterizing hamadryas leader males. Am J Phys Anthropol, 2015. © 2015 Wiley Periodicals, Inc.

Sexual selection is one of the earliest areas of interest in evolutionary biology. And yet, the evolutionary history of sexually dimorphic traits remains poorly characterized for most vertebrate lineages. Here, we report on evidence for... more

Sexual selection is one of the earliest areas of interest in evolutionary biology. And yet, the evolutionary history of sexually dimorphic traits remains poorly characterized for most vertebrate lineages. Here, we report on evidence for the early evolution of dimorphism within a model mammal group, the pinnipeds. Pinnipeds show a range of sexual dimorphism and mating systems that span the extremes of modern mammals, from monomorphic taxa with isolated and dispersed mating to extreme size dimorphism with highly ordered polygynous harem systems. In addition, the degree of dimorphism in pinnipeds is closely tied to mating system, with strongly dimorphic taxa always exhibiting a polygynous system, and more monomorphic taxa possessing weakly polygynous systems. We perform a comparative morphological description, and provide evidence of extreme sexual dimorphism (similar to sea lions), in the Miocene-aged basal pinniped taxon Enaliarctos emlongi. Using a geometric morphometric approach and combining both modern and fossil taxa we show a close correlation between mating system and sex-related cranial dimorphism, and also reconstruct the ancestral mating system of extant pinnipeds as highly polygynous. The results suggest that sexual dimorphism and extreme polygyny in pinnipeds arose by 27 Ma, in association with changing climatic conditions.