More Like this

1. Longer telomeres during early life predict higher lifetime reproductive success in females but not males

   https://doi.org/10.1098/rspb.2021.0560  

   Heidinger, Britt J.; Kucera, Aurelia C.; Kittilson, Jeff D.; Westneat, David F. (May 2021, Proceedings of the Royal Society B: Biological Sciences)

   null (Ed.)

   The mechanisms that contribute to variation in lifetime reproductive success are not well understood. One possibility is that telomeres, conserved DNA sequences at chromosome ends that often shorten with age and stress exposures, may reflect differences in vital processes or influence fitness. Telomere length often predicts longevity, but longevity is only one component of fitness and little is known about how lifetime reproductive success is related to telomere dynamics in wild populations. We examined the relationships between telomere length beginning in early life, telomere loss into adulthood and lifetime reproductive success in free-living house sparrows ( Passer domesticus ). We found that females, but not males, with longer telomeres during early life had higher lifetime reproductive success, owing to associations with longevity and not reproduction per year or attempt. Telomeres decreased with age in both sexes, but telomere loss was not associated with lifetime reproductive success. In this species, telomeres may reflect differences in quality or condition rather than the pace of life, but only in females. Sexually discordant selection on telomeres is expected to influence the stability and maintenance of within population variation in telomere dynamics and suggests that any role telomeres play in mediating life-history trade-offs may be sex specific. 

   more » « less
2. Fast and slow-paced reproductive life history across native and invasive populations of a predatory marine snail

   https://doi.org/10.1101/2025.05.15.654356  

   Rugila, Allison L; Bucari, Emily; Rawson, Emma; Schlaug, Amara L; Komoroske, Lisa M; Cheng, Brian S (May 2025, bioRxiv)

   Abstract Populations across a species’ range may be locally adapted, and failure to recognize this variation can lead to inaccurate predictions of their resilience or vulnerability to climate change. Because life history traits are directly linked to fitness, life history theory can serve as a useful framework for evaluating how populations within species may respond to rapid environmental change. However, relatively few studies quantify multiple life history traits and their tradeoffs across many populations, especially in marine taxa. Here, we used a 10-month laboratory experiment to quantify a suite of reproductive traits in populations spanning the strongest latitudinal temperature gradient in the world’s coastal oceans. We examined reproductive traits in wild-captured adults exposed to simulated local conditions for 7 native Atlantic and 4 introduced Pacific populations of the marine predatory gastropodUrosalpinx cinerea. Our data reveals that reproductive season length, the number of reproductive attempts, and annual fecundity unimodally peaked at mid-latitude populations, the species’ range-center. Introduced populations had comparably few spawning attempts and low fecundity despite a longer reproductive period in a less seasonal environment. We then conducted a second experiment quantifying thermal tolerance of developing embryos from 3 native populations, which revealed high sensitivity to temperature at early life stages but weak population differentiation. Taken together, our data reveal stark differences in reproduction that appear to reflect “fast” and “slow” paced lifestyles, which may maximize fitness by spreading the risk of reproductive failure over a single season or lifetime. Our results indicate that warm range-edge populations are highly vulnerable to warming, as low embryonic thermal tolerance may shorten the spawning season and warming is likely to reduce fecundity. This study highlights heterogeneity in life history traits across marine populations that may underlie differential vulnerability to climate warming. Open research statementAll data and code will be publicly available via Figshare and the NSF Biological and Chemical Oceanography Data Management Office (BCO-DMO). 

   more » « less
3. Inbreeding avoidance and cost in a small, isolated trout population

   https://doi.org/10.1098/rspb.2024.1164  

   Bell, Donovan A; Kovach, Ryan P; Whiteley, Andrew R (November 2024, Proceedings of the Royal Society B: Biological Sciences)

   The persistence of small populations is influenced by the degree and cost of inbreeding, with the degree of inbreeding depending on whether close-kin mating is passively or actively avoided. Few studies have simultaneously studied these factors. We examined inbreeding in a small, isolated population of westslope cutthroat trout using extensive genetic and demographic data. Passive inbreeding avoidance was low, with predicted lifetime dispersal of approximately 36 and 74 m for females and males, respectively. Additionally, we found limited evidence for active inbreeding avoidance during reproduction. Relatives remained spatially clustered into adulthood, and observed relatedness among mate pairs was greater than expected under random mating by 0.09, suggesting that inbreeding is a concern in this population. Further, we examined sex-specific inbreeding depression throughout the life cycle and provide evidence for inbreeding depression in some fitness components, including family size, juvenile survival and reproductive success. Our results suggest that, in an at-risk trout population, limited passive and active inbreeding avoidance lead to a higher degree of inbreeding than expected under random mating. Observed inbreeding, along with evidence for fitness reduction due to inbreeding depression, could put the population at a heightened risk of decline or extirpation. 

   more » « less
4. Adaptation to warm environments with a fast pace of life in a marine predatory snail

   https://doi.org/10.1101/2025.06.20.660751  

   Dwane, Christopher; Komoroske, Lisa M; Rugila, Allison L; Bentley, Blair P; Rawson, Emma; Clark, Elizabeth; Nichols, Gillian; Newbrey, Mikayla; Bucari, Emily; Yan, Chance; et al (June 2025, bioRxiv)

   Understanding how latitudinal temperature variation shapes local adaptation of life history strategies is crucial for predicting future responses to warming. Contrasting predictive frameworks explain how growth and other life history traits may respond to differing selective pressures across latitude. However, these frameworks have rarely been explored within the context of fluctuating environmental temperatures across longer (i.e., seasonal) time scales experienced in nature. Furthermore, consequences of growth differences for other aspects of fitness, including reproductive output, remain unclear. Here, we conducted a long-term (17-month) simulated reciprocal transplant experiment to examine local adaptation in two populations of the predatory marine snail Urosalpinx cinerea separated by 8.6 degrees latitude (1000 km). We reared F1 offspring under two seasonally fluctuating temperature regimes (warm and cold, simulating field thermal conditions experienced by low and high latitude populations, respectively), quantifying temporal patterns in growth, maturation, and reproductive output. We identified striking divergence in life-history strategies between populations in the warm regime, with offspring from the low latitude population achieving greater growth in their first year, and high reproductive output coupled with reduced growth in their second year. In contrast, the high latitude population grew slower in their first year, but eventually attained larger sizes in their second year, at the expense of reduced reproductive output. Responses were consistent with this in the cold regime, although growth and reproductive output was reduced in both populations. Our data provides support for adaptive divergence across latitude consistent with the Pace-of-Life hypothesis, with the low latitude population selected for a fast-paced life characterized by rapid development and early reproduction. In contrast, the high latitude population exhibited slower growth and delayed maturation. Our results highlight the potential limitations of short-term comparisons of growth without considering processes over longer time scales that may exhibit seasonal temperature variation and ontogenetic shifts in energy allocation and imply a radical reshaping of physiological performance and life history traits across populations under climate change. 

   more » « less
5. Concurrent threats and extinction risk in a long‐lived, highly fecund vertebrate with parental care

   https://doi.org/10.1002/eap.2946  

   Brooks, George C; Hopkins, William A; Kindsvater, Holly K (March 2024, Ecological Applications)

   Abstract Detecting declines and quantifying extinction risk of long‐lived, highly fecund vertebrates, including fishes, reptiles, and amphibians, can be challenging. In addition to the false notion that large clutches always buffer against population declines, the imperiled status of long‐lived species can often be masked by extinction debt, wherein adults persist on the landscape for several years after populations cease to be viable. Here we develop a demographic model for the eastern hellbender (Cryptobranchus alleganiensis), an imperiled aquatic salamander with paternal care. We examined the individual and interactive effects of three of the leading threats hypothesized to contribute to the species' demise: habitat loss due to siltation, high rates of nest failure, and excess adult mortality caused by fishing and harvest. We parameterized the model using data on their life history and reproductive ecology to model the fates of individual nests and address multiple sources of density‐dependent mortality under both deterministic and stochastic environmental conditions. Our model suggests that high rates of nest failure observed in the field are sufficient to drive hellbender populations toward a geriatric age distribution and eventually to localized extinction but that this process takes decades. Moreover, the combination of limited nest site availability due to siltation, nest failure, and stochastic adult mortality can interact to increase the likelihood and pace of extinction, which was particularly evident under stochastic scenarios. Density dependence in larval survival and recruitment can severely hamper a population's ability to recover from declines. Our model helps to identify tipping points beyond which extinction becomes certain and management interventions become necessary. Our approach can be generalized to understand the interactive effects of various threats to the extinction risk of other long‐lived vertebrates. As we face unprecedented rates of environmental change, holistic approaches incorporating multiple concurrent threats and their impacts on different aspects of life history will be necessary to proactively conserve long‐lived species. 

   more » « less