COHORT DYNAMICS OF A CAENIS LATIPENNIS POPULATION Cohort dynamics of an over- wintering Caenis latipennis population in Honey Creek, Oklahoma, U.S.A (original) (raw)
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The life history and production of Caenis latipennis Banks (Ephemeroptera: Caenidae) is described from Honey Creek, Oklahoma. Emergence behavior, fecundity, voltinism, and secondary production were analyzed. C. latipennis had an extended emergence with Þve peaks. Females emerged, molted, mated, and oviposited in an estimated 37 min. Mean fecundity was 888.4 291.9 eggs per individual (range, 239 Ð1,576). Adult female head capsule widths in spring were signiÞcantly larger than in summer and fall. Compared with the other seasons, fecundity was signiÞcantly higher in early summer when densities were lowest. C. latipennis exhibited a multivoltine life cycle with Þve overlapping generations. Estimated annual secondary production for C. latipennis in Honey Creek was 4,404.28 mg/m 2 /yr, mean standing stock biomass was 274.64 mg/m 2 /yr, cohort production:biomass ratio was 5.79, and the annual production/biomass rate was 16.04/yr/yr. Standing stock biomass ranged from 7.6 to 705.4 mg/m 2 during the year. Standing stock biomass did not vary signiÞcantly among seasons.
Annals of the Entomological Society of America, 2006
The life history and production of Caenis latipennis Banks (Ephemeroptera: Caenidae) is described from Honey Creek, Oklahoma. Emergence behavior, fecundity, voltinism, and secondary production were analyzed. C. latipennis had an extended emergence with Þve peaks. Females emerged, molted, mated, and oviposited in an estimated 37 min. Mean fecundity was 888.4 Ϯ 291.9 eggs per individual (range, 239 Ð1,576). Adult female head capsule widths in spring were signiÞcantly larger than in summer and fall. Compared with the other seasons, fecundity was signiÞcantly higher in early summer when densities were lowest. C. latipennis exhibited a multivoltine life cycle with Þve overlapping generations. Estimated annual secondary production for C. latipennis in Honey Creek was 4,404.28 mg/m 2 /yr, mean standing stock biomass was 274.64 mg/m 2 /yr, cohort production:biomass ratio was 5.79, and the annual production/biomass rate was 16.04/yr/yr. Standing stock biomass ranged from 7.6 to 705.4 mg/m 2 during the year. Standing stock biomass did not vary signiÞcantly among seasons.
Hatching delays in great tits and blue tits in response to an extreme cold spell: a long-term study
International journal of biometeorology, 2018
Variation in ambient temperature affects various life stages of organisms. It has been suggested that climate change not only implies higher global temperatures but also more unpredictable weather and more frequent extreme weather events. Temperature has a major influence on the optimal laying-incubation-hatching dates of insectivorous passerines, because it poses energetic constraints and affects the timing of food abundance. We have been studying breeding characteristics of great tits Parus major and blue tits Cyanistes caeruleus in two areas, an urban parkland and a deciduous forest, around the city of Łódź since 2002. During the egg-laying period in 2017, both tit species at both study areas faced an unusual cold spell as reflected by a sudden decrease in the mean ambient temperature to ca. 2-3 °C for about 5 days, which caused mean hatching delays of up to 6 days. Since flexibility of behavior plays a major role in adjusting to unpredictable weather conditions, examining its li...
Ecological Monographs, 2016
Geographic range shifts in species' distributions, due to climate change, imply altered dynamics at both their northern and southern range limits, or at upper and lower elevational limits. There is therefore a need to identify specific weather or climate variable(s), and life stages or cohorts on which they act, and how these affect population growth. Identifying such variables permits prediction of population increase or decline under a changing climate, and shifts in a species' geographic range. For relatively well studied groups, such as butterflies, geographic range shifts are well documented, but weather variables and mechanisms causing those shifts are not well known. The Holarctic butterfly genus Parnassius (Papilionidae) inhabits northern and alpine environments subject to variable and extreme weather. As such, Parnassius species are vulnerable not only to long-term changes in average conditions but especially to short-term extreme weather events. We use population growth estimates for the alpine butterfly, Parnassius smintheus, from 21 populations in the Rocky Mountains of Canada over a 20-yr interval combined with techniques of machine learning (randomForests) and parametric modeling to identify the important weather variables determining population growth. We do this to determine the seasons and life stages of P. smintheus most affected by climate change. Extreme minimum and maximum temperatures in November, in combination with November snowfall, affect annual population growth most, more so than do mean temperatures in November, and more so than weather at any other time of year. Populations decline both in years with low extreme minimum temperatures in November and especially in years with high extreme maximum temperatures in November, indicating that overwintering eggs are particularly vulnerable to early-winter weather. Snowfall ameliorates the negative effects of extreme temperatures, particularly for extreme warm events. Results provide insight into biological mechanisms by which overwintering eggs might be affected by early winter weather. Shortterm extreme weather in November, acting on a single pivotal life stage (egg) is a far better predictor of population change of alpine P. smintheus butterflies than is the general index of climate, the Pacific Decadal Oscillation.
Entomologia Experimentalis et Applicata, 2012
As the growing season is expected to begin earlier under climate change, insects should initiate reproduction several days or weeks earlier than they used to. In eastern Canada, hemlock looper (HL) Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae) females generally oviposit in September, with eggs entering an obligatory diapause quickly after their deposition. We therefore simulated an early start of the HL reproduction cycle of 2, 4, 6, or 8 weeks to examine the extent to which freshly laid eggs from two populations (island and mainland) can withstand exposure to four temperature conditions (15, 20, 25°C, or fluctuating temperature in an outdoor insectary), with all treatments ending on 1 September 2007. On this date, half the eggs from each population were immediately incubated at 15°C, while the rest were stored in an outdoor insectary until their incubation at 15°C the following spring. In a separate experiment, the effect of temperature on pre-diapause duration was determined from the number of days required for eggs to change colour after oviposition. The pre-diapause phase was completed faster as temperature increased. Regardless of incubation date and population, percent hatch decreased significantly after 6-8 weeks of exposure to 25°C or in the outdoor insectary. Under most treatments, the odds of dying as pharate larvae increased with exposure duration. When eggs were incubated at 15°C immediately after treatment, time to hatch and diapause duration remained constant over treatments, except at 25°C when they both decreased. After 8 weeks of exposure to 15 or 20°C, eggs transferred outdoors were more likely to hatch precociously than those exposed to 25°C or insectary conditions. Globally, mortality seemed greater among eggs stored outdoors than among those kept indoors. Most eggs that survived the winter hatched synchronously after incubation in spring. Overall, larger eggs from the island population survived better than smaller eggs from the mainland population.
Entomologia Experimentalis et Applicata, 2009
Embryonic dormancy characteristics of the hemlock looper (HL), Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae), an important coniferous defoliator, were investigated using eggs from an island (Newfoundland) and a mainland (Quebec) population in eastern Canada. We determined (1) the pre-diapause duration or time required for eggs to change color at 15°C, under L16:D8 and L12:D12, (2) the percent hatch and time to hatch of early-diapausing eggs that were, as of 1 September, either (a) incubated under each combination of three photoperiods (L16:D8, L12:D12, or L8:D16) and three temperatures (15, 20, or 25°C) or (b) stored outdoors prior to their monthly incubation (October-May) under the same treatments, and (3) the diapause duration at 15°C. The two HL ecotypes completed their pre-diapause phase in ca. 15 days under long-day photoperiod. In the mainland ecotype, photoperiod did not influence the pre-diapause duration. Regardless of photoperiod and ecotype, only eggs incubated continuously at 15°C hatched successfully after ca. 120 days. Temperature was the most important factor modulating the dormancy of eggs acclimated outdoors, in both ecotypes. From October to December (diapause phase), percent egg hatch at 20 and 25°C increased from low (20%) to levels similar to those obtained at 15°C (70%). These percentages remained stable throughout the post-diapause phase (January-May). Time to hatch, which was shorter at warmer temperatures, decreased from October to December at all temperatures. It remained stable from January to March (quiescence), however, and declined thereafter. Eggs from the island were heavier than those from the mainland and their odds of hatching were 2.3 times higher. At 15°C, diapause lasted ca. 90 days. Our findings indicate that eggs from the two HL ecotypes (1) undergo an obligatory diapause, (2) complete diapause without pre-exposure to cold, (3) respond similarly to photoperiod and temperature during diapause and post-diapause, and (4) do not hatch successfully after prolonged exposure to high temperatures.
1. We examined the influence of local weather conditions on reproductive success, timing of breeding and survival in a population of a multi-brooded ground nesting passerine (woodlark Lullula ar-borea) over 35 years. 2. Woodlarks laid larger clutches when rainfall was low and temperature high during the egg-laying and pre-laying period. Nest success increased with higher temperatures during the nesting period. In successful nests, the number of chicks fledged per egg laid was greater when weather was drier during the brood stage. 3. Although woodlarks bred earlier in years with warmer early spring temperatures, with the onset of breeding varying by 25 days, there was no significant advance in the onset of breeding over the 35 years of study, due to considerable inter-annual variability, and no overall trend, in weather. 4. Simulation modelling of annual reproductive output demonstrated that earlier breeding could increase productivity by 23AE5% in the warmest compared to the coldest year, due to birds having more nesting attempts. Other effects of weather on productivity affected breeding output to a lesser extent. 5. Effects of weather on productivity were minor compared to an increased rate of nest predation through the period of study, which reduced productivity by 49AE8% by 2004 compared to 1971. 6. Turning points analysis identified three distinct demographic periods: from1971 to 1988 the population grew slowly, during 1988–1999 the population grew rapidly, but after 1999 the population declined. Increased population growth after 1988 was associated with higher first-year survival rates (estimated using a population model). Population decline after 1999 was caused by a combination of reduced productivity (resulting from increased nest failure rates attributed to predation) and lower first-year survival rates, that appear unrelated to winter temperature. 7. Climate change (long-term changes in weather) did not explain the marked changes observed in the population trajectory over 35 years. We suggest that understanding effects of both climate and habitat change on populations is essential in predictive population modelling.
Journal of Ornithology
Environmental conditions affect incubation behavior, but whilst the effect of ambient temperature is studied and still controversially discussed, the role of precipitation is unknown. Here, we analyzed the effect of local ambient temperature and precipitation on incubation behavior of female Great Tits (Parus major) and accounted for diurnal patterns of weather conditions. We monitored the incubation behavior of females using temperature data loggers, thus identifying periods of staying inside nest boxes incubating, and leaving nest boxes (off-bout). In total, 685 single off-bouts were analyzed between the first 8 days of incubation directly after clutches were completed. Our study showed that whilst precipitation had no effect on incubation behavior, number and duration of off-bouts were negatively related to ambient temperature, which varied throughout the day. We showed that females took longer off-bouts during low-temperature early mornings, which may result from the need to for...