Biology subjects

Schindler, D. E.

Publications and source records attributed to Schindler, D. E..

4 recordsLinked to original sources

bioRxiv2024

Marine spatial planning to enhance coral adaptive potential

Ocean warming interacts with local stressors to negatively affect coral reefs. The adaptive capacity of reefs to survive these stressors is driven by ecological and evolutionary processes occurring at multiple spatial scales. Marine protected area (MPA) networks are one solution that can address both local and regional threats, yet the impacts of MPA network design on adaptive processes remains unclear. In this paper, we used an eco-evolutionary model to simulate hypothetical MPA configurations in the Caribbean, Southwest Pacific and Coral Triangle under projected warming. We found that protecting thermal refugia (i.e., cooler reefs) largely benefited corals inside the refugia while other reefs declined. In contrast, protecting a diverse habitat portfolio led to increased coral cover both inside and outside of the MPA network. We then quantified the thermal habitat and connectivity representations of reefs both inside and outside existing MPA networks across each region. Most strikingly, reefs in current MPA networks in the Southwest Pacific and Coral Triangle are approximately 2 {degrees}C cooler than reefs outside the MPA networks, while the Caribbeans MPA network is approximately 1 {degrees}C warmer than reefs outside the network, based on mean temperatures from 2008-2018. These results suggest that the Caribbean MPA network is poised to protect sources of warm-adapted larvae but not destinations, and the opposite is true of the Southwest Pacific and Coral Triangle. Our results suggest that 1) by protecting sites with particular temperature and connectivity characteristics, marine spatial planning may alter eco-evolutionary processes to enhance or inhibit the adaptive capacity of a reef network and 2) the distribution, extent, and effectiveness of local interventions have the potential to affect regional distributions of coral cover beyond what would be expected from local benefits alone, due to the potentially wide-reaching effects of larval dispersal and gene flow.

ecology↗

bioRxiv2024

Accounting for salmon body size declines in fishery management can reduce conservation risks

Changes in population demographic structure can have tangible but unknown effects on management effectiveness. Fishery management of Pacific salmon is often informed by estimates of the number of spawners expected to produce maximum sustainable yield (SMSY), which implicitly assumes that reproductive output per spawner does not change over time. However, many salmon populations have experienced long-term trends in age, sex, and length-at-age compositions that have resulted in smaller body sizes of mature fish. We present an empirically-based simulation approach for evaluating management implications of declining reproductive output that results from shifting demographics. We simulated populations with or without demographic trends, selective or unselective harvests, and harvest policies based on assessment methods that did or did not account for demographic trends when estimating SMSY. A management strategy evaluation showed that expected mean harvests and run sizes were reduced when populations exhibited negative demographic trends. Reduced abundances and increased conservation risks could be partially mitigated by using a stock-recruit analysis based on egg mass instead of spawner abundance, or by using a precautionary management strategy where target escapements were higher than the estimated SMSY, especially in fisheries that selectively removed large fish. Accounting for demographic trends in stock-recruit analyses resulted in up to 25% higher run sizes and up to 20% lower conservation risks compared to traditional methods when trends toward smaller, younger, and male-biased runs were present in the population. Conservation of population demographic structure may be critical for sustaining productive fish populations and their benefits to ecosystems and people.

ecology↗

bioRxiv2021

Evolution and connectivity influence the persistence and recovery of coral reefs under climate change in the Caribbean, Southwest Pacific, and Coral Triangle

Corals are experiencing unprecedented decline from climate change-induced mass bleaching events. Dispersal not only contributes to coral reef persistence through demographic rescue but can also hinder or facilitate evolutionary adaptation. Locations of reefs that are likely to survive future warming therefore remain largely unknown, particularly within the context of both ecological and evolutionary processes across complex seascapes that differ in temperature range, strength of connectivity, network size, and other characteristics. Here, we used eco-evolutionary simulations to examine coral adaptation to warming across reef networks in the Caribbean, the Southwest Pacific, and the Coral Triangle. We assessed the factors associated with coral persistence in multiple reef systems to understand which results are general and which are sensitive to particular geographic contexts. We found that evolution can be critical in preventing extinction and facilitating the long-term recovery of coral communities in all regions. Furthermore, the strength of immigration to a reef (destination strength) and current sea surface temperature robustly predicted reef persistence across all reef networks and across temperature projections. However, we found higher initial coral cover, slower recovery, and more evolutionary lag in the Coral Triangle, which has a greater number of reefs and more larval settlement than the other regions. We also found the lowest projected future coral cover in the Caribbean. These findings suggest that coral reef persistence depends on ecology, evolution, and habitat network characteristics, and that, under an emissions stabilization scenario (RCP 4.5), recovery may be possible over multiple centuries.

ecology↗

bioRxiv2019

Y-chromosome haplotypes drive variation in size and age at maturity in male Chinook salmon

Variation in size and age at maturity is an important component of life history that is influenced both by environmental and genetic factors. In salmonids, large size confers a direct reproductive advantage through increased fecundity and egg quality in females, while larger males gain a reproductive advantage by monopolizing access to females. In addition, variation in size and age at maturity in males can be associated with different reproductive strategies; younger smaller males may gain reproductive success by sneaking in among mating pairs. In both sexes there is a trade-off between older age and increased reproductive success and increased risk of mortality by delaying reproduction. We identified four Y-chromosome haplogroups that showed regional and population-specific variation in frequency using RADseq data for 21 populations of Alaska Chinook salmon. We then characterized the range-wide distribution of these haplogroups using GT-seq assays. These haplogroups exhibited associations with size at maturity in multiple populations suggesting that the lack of recombination between X and Y-chromosomes has allowed Y-chromosome haplogroups to capture different alleles that influence size at maturity. Ultimately, conservation of life history diversity in Chinook salmon may require conservation of Y-chromosome haplotype diversity.

evolutionary biology↗