Conserv Biol
February 2025
Plans for expanding protected area systems (prioritizations) need to fulfill conservation objectives. They also need to account for other factors, such as economic feasibility and anthropogenic land-use requirements. Although prioritizations are often generated with decision support tools, most tools have limitations that hinder their use for decision-making.
View Article and Find Full Text PDFImpacts of immigration on micro-evolution and population dynamics fundamentally depend on net rates and forms of resulting gene flow into recipient populations. Yet, the degrees to which observed rates and sex ratios of physical immigration translate into multi-generational genetic legacies have not been explicitly quantified in natural meta-populations, precluding inference on how movements translate into effective gene flow and eco-evolutionary outcomes. Our analyses of three decades of complete song sparrow (Melospiza melodia) pedigree data show that multi-generational genetic contributions from regular natural immigrants substantially exceeded those from contemporary natives, consistent with heterosis-enhanced introgression.
View Article and Find Full Text PDFAbstractThe fitness of immigrants and their descendants produced within recipient populations fundamentally underpins the genetic and population dynamic consequences of immigration. Immigrants can in principle induce contrasting genetic effects on fitness across generations, reflecting multifaceted additive, dominance, and epistatic effects. Yet full multigenerational and sex-specific fitness effects of regular immigration have not been quantified within naturally structured systems, precluding inference on underlying genetic architectures and population outcomes.
View Article and Find Full Text PDFEcogeographic rules denote spatial patterns in phenotype and environment that may reflect local adaptation as well as a species' capacity to adapt to change. To identify genes underlying Bergmann's Rule, which posits that spatial correlations of body mass and temperature reflect natural selection and local adaptation in endotherms, we compare 79 genomes from nine song sparrow (Melospiza melodia) subspecies that vary ~300% in body mass (17 - 50 g). Comparing large- and smaller-bodied subspecies revealed 9 candidate genes in three genomic regions associated with body mass.
View Article and Find Full Text PDFIndividuals vary in their immune genotype, inbreeding coefficient f, immune responses, survival to adulthood, and adult longevity. However, whether immune genes predict survival or longevity, whether such relationships are mediated through immune responses, and how f affects immune genotype remain unclear. We use a wild song sparrow (Melospiza melodia) population in which survival to adulthood, adult longevity, and f were measured precisely, and in which immune responses have previously been assessed.
View Article and Find Full Text PDFThe rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates.
View Article and Find Full Text PDFA capacity for rapid adaptation should enhance the persistence of populations subject to temporal and spatial heterogeneity in natural selection, but examples from nature remain scarce. () is a winter annual that exhibits local adaptation to browsing by ungulates and hypothesized to show context-dependent trade-offs in traits affecting success in competition versus resistance or tolerance to browsing. We grew P.
View Article and Find Full Text PDFPredicting the geographic range of species and their response to climatic variation and change are entwined goals in conservation and evolutionary ecology. Species distribution models (SDMs) are foundational in this effort and used to visualize the geographic range of species as the spatial representation of its realized niche. SDMs are also used to forecast range shifts under climate change, but often in the absence of empirical evidence that climate limits population growth.
View Article and Find Full Text PDFImmigration into small recipient populations is expected to alleviate inbreeding and increase genetic variation, and hence facilitate population persistence through genetic and/or evolutionary rescue. Such expectations depend on three standard assumptions: that immigrants are outbred, unrelated to existing natives at arrival, and unrelated to each other. These assumptions are rarely explicitly verified, including in key field systems in evolutionary ecology.
View Article and Find Full Text PDFOngoing adaptive evolution, and resulting "evolutionary rescue" of declining populations, requires additive genetic variation in fitness. Such variation can be increased by gene flow resulting from immigration, potentially facilitating evolution. But, gene flow could in fact constrain rather than facilitate local adaptive evolution if immigrants have low additive genetic values for local fitness.
View Article and Find Full Text PDFElucidating forces capable of driving species diversification in the face of gene flow remains a key goal in evolutionary biology. Song sparrows, Melospiza melodia, occur as 25 subspecies in diverse habitats across North America, are among the continent's most widespread vertebrate species, and are exemplary of many highly variable species for which the conservation of locally adapted populations may be critical to their range-wide persistence. We focus here on six morphologically distinct subspecies resident in the San Francisco Bay region, including three salt-marsh endemics and three residents in upland and riparian habitats adjacent to the Bay.
View Article and Find Full Text PDFQuantifying additive genetic variances and cross-sex covariances in reproductive traits, and identifying processes that shape and maintain such (co)variances, is central to understanding the evolutionary dynamics of reproductive systems. Gene flow resulting from among-population dispersal could substantially alter additive genetic variances and covariances in key traits in recipient populations, thereby altering forms of sexual conflict, indirect selection, and evolutionary responses. However, the degree to which genes imported by immigrants do in fact affect quantitative genetic architectures of key reproductive traits and outcomes is rarely explicitly quantified.
View Article and Find Full Text PDFSpatial variation in the occurrence of browsing ungulates can drive local adaptation in plant traits but also lead to trade-offs among traits potentially enhancing competitive ability versus resistance or tolerance to browsing. Plectritis congesta populations co-occurring on islands with and without ungulates offer striking examples of population-level variation in traits, such as plant height and fruit morphology, which may also affect fitness. We monitored split-plot common gardens exposed to and protected from browsing ungulates for 5 yr to test for local adaptation (local vs.
View Article and Find Full Text PDFInclusive fitness theory predicts that parental care will vary with relatedness between potentially caring parents and offspring, potentially shaping mating system evolution. Systems with extra-pair paternity (EPP), and hence variable parent-brood relatedness, provide valuable opportunities to test this prediction. However, existing theoretical and empirical studies assume that a focal male is either an offspring's father with no inbreeding, or is completely unrelated.
View Article and Find Full Text PDFDecision-support tools are commonly used to maximize return on investments (ROI) in conservation. We evaluated how the relative value of information on biodiversity features and land cost varied with data structure and variability, attributes of focal species and conservation targets, and habitat suitability thresholds for contrasting bird communities in the Pacific Northwest of North America. Specifically, we used spatial distribution maps for 20 bird species, land values, and an integer linear programming model to prioritize land units (1 km) that met conservation targets at the lowest estimated cost (hereafter 'efficiency').
View Article and Find Full Text PDFTheory suggests that different taxa having colonized a similar, challenging environment will show parallel or lineage-specific adaptations to shared selection pressures, but empirical examples of parallel evolution in independent taxa are exceedingly rare. We employed comparative genomics to identify parallel and lineage-specific responses to selection within and among four species of North American sparrows that represent four independent, post-Pleistocene colonization events by an ancestral, upland subspecies and a derived salt marsh specialist. We identified multiple cases of parallel adaptation in these independent comparisons following salt marsh colonization, including selection of 12 candidate genes linked to osmoregulation.
View Article and Find Full Text PDFBiological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive.
View Article and Find Full Text PDFAppropriately defining and enumerating "fitness" is fundamental to explaining and predicting evolutionary dynamics. Yet, general theoretical concepts of fitness are often hard to translate into quantities that can be measured in wild populations experiencing complex environmental, demographic, genetic, and selective variation. Although the "fittest" entities might be widely understood to be those that ultimately leave most descendants at some future time, such long-term legacies can rarely be measured, impeding evaluation of the degree to which tractable short-term metrics of individual fitness could potentially serve as useful direct proxies.
View Article and Find Full Text PDFLimited knowledge of the distribution, abundance, and habitat associations of migratory species hinders effective conservation actions. We use Neotropical migratory birds as a model group to compare approaches to prioritize land conservation needed to support ≥30% of the global abundances of 117 species. Specifically, we compare scenarios from spatial optimization models to achieve conservation targets by: 1) area requirements for conserving >30% abundance of each species for each week of the year independently vs.
View Article and Find Full Text PDFQuantifying sex-specific additive genetic variance (V ) in fitness, and the cross-sex genetic correlation (r ), is prerequisite to predicting evolutionary dynamics and the magnitude of sexual conflict. Further, quantifying V and r in underlying fitness components, and genetic consequences of immigration and resulting gene flow, is required to identify mechanisms that maintain V in fitness. However, these key parameters have rarely been estimated in wild populations experiencing natural environmental variation and immigration.
View Article and Find Full Text PDFVariation in immune gene sequences is known to influence resistance to infectious diseases and parasites, and hence survival and mate choice, across animal taxa. Toll-like receptors (TLRs) comprise one essential gene family in the vertebrate innate immune system and recognize evolutionarily conserved structures from all major microorganism classes. However, the causes and consequences of TLR variation in passerine birds remain largely unexplored.
View Article and Find Full Text PDFThe evolutionary benefits of simultaneous polyandry (female multiple mating within a single reproductive event) remain elusive. One potential benefit could arise if polyandry alters sibship structures and consequent relationships and relatedness among females' descendants, thereby intrinsically reducing future inbreeding risk (the indirect inbreeding avoidance hypothesis). However such effects have not been quantified in naturally complex mating systems that also encompass iteroparity, overlapping generations, sequential polyandry, and polygyny.
View Article and Find Full Text PDFInbreeding is widely hypothesized to shape mating systems and population persistence, but such effects will depend on which traits show inbreeding depression. Population and evolutionary consequences could be substantial if inbreeding decreases sperm performance and hence decreases male fertilization success and female fertility. However, the magnitude of inbreeding depression in sperm performance traits has rarely been estimated in wild populations experiencing natural variation in inbreeding.
View Article and Find Full Text PDFStudies of the phenological responses of animals to climate change typically emphasize the initiation of breeding although climatic effects on the cessation and length of the breeding period may be as or more influential of fitness. We quantified links between climate, the cessation and length of the breeding period, and individual survival and reproduction using a 34-year study of a resident song sparrow (Melospiza melodia) population subject to dramatic variation in climate. We show that the cessation and length of the breeding period varied strongly across years, and predicted female annual fecundity but not survival.
View Article and Find Full Text PDFTheory predicts that reproduction will change as individuals near the end of their lives by either increasing reproductive allocation (terminal allocation hypothesis) or decreasing allocation (senescence hypothesis) toward the end of life. Although senescence has received more support, few studies examine how both age and years to death influence late-life reproduction. We used a 37-yr study of Song Sparrows (Melospiza melodia) to ask how age and years to death influenced reproductive allocation late in life.
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