scholarly journals Postreproductive killer whale grandmothers improve the survival of their grandoffspring

2019 ◽  
Vol 116 (52) ◽  
pp. 26669-26673 ◽  
Author(s):  
Stuart Nattrass ◽  
Darren P. Croft ◽  
Samuel Ellis ◽  
Michael A. Cant ◽  
Michael N. Weiss ◽  
...  
Keyword(s):  
Life History ◽  
Inclusive Fitness ◽  
Killer Whale ◽  
Mammalian Species ◽  
Life History Trait ◽  
Killer Whales ◽  
Reproductive Conflict ◽  
Significant Survival ◽  
Fitness Benefits ◽  
Difficult Times

Understanding why females of some mammalian species cease ovulation prior to the end of life is a long-standing interdisciplinary and evolutionary challenge. In humans and some species of toothed whales, females can live for decades after stopping reproduction. This unusual life history trait is thought to have evolved, in part, due to the inclusive fitness benefits that postreproductive females gain by helping kin. In humans, grandmothers gain inclusive fitness benefits by increasing their number of surviving grandoffspring, referred to as the grandmother effect. Among toothed whales, the grandmother effect has not been rigorously tested. Here, we test for the grandmother effect in killer whales, by quantifying grandoffspring survival with living or recently deceased reproductive and postreproductive grandmothers, and show that postreproductive grandmothers provide significant survival benefits to their grandoffspring above that provided by reproductive grandmothers. This provides evidence of the grandmother effect in a nonhuman menopausal species. By stopping reproduction, grandmothers avoid reproductive conflict with their daughters, and offer increased benefits to their grandoffspring. The benefits postreproductive grandmothers provide to their grandoffspring are shown to be most important in difficult times where the salmon abundance is low to moderate. The postreproductive grandmother effect we report, together with the known costs of late-life reproduction in killer whales, can help explain the long postreproductive life spans of resident killer whales.

scholarly journals A long post-reproductive lifespan is a shared trait among genetically distinct killer whale populations

2021 ◽  
Author(s):  
Mia Nielsen ◽  
Samuel Ellis ◽  
Jared Towers ◽  
Thomas Doniol-Valcroze ◽  
Daniel Franks ◽  
...  
Keyword(s):  
Social Structure ◽  
Killer Whale ◽  
Demographic Data ◽  
Reproductive Period ◽  
Substantial Variation ◽  
Killer Whales ◽  
Reproductive Conflict ◽  
Demographic Patterns ◽  
General Prediction

The extended female post-reproductive lifespan found in humans and some toothed whales remains an evolutionary puzzle. Theory predicts demographic patterns resulting in increased female relatedness with age (kinship dynamics) can select for a prolonged post-reproductive lifespan due to the combined costs of inter-generational reproductive conflict and benefits of late-life helping. Here we test this prediction using >40 years of longitudinal demographic data from the sympatric yet genetically distinct killer whale ecotypes: resident and Bigg’s killer whales. The female relatedness with age is predicted to increase in both ecotypes, but with a less steep increase in Bigg’s due to their different social structure. Here, we show that there is a significant post-reproductive lifespan in both ecotypes with >30% of adult female years being lived as post-reproductive, supporting the general prediction that an increase in local relatedness with age predisposes the evolution of a post-reproductive lifespan. Differences in the magnitude of kinship dynamics however, did not influence the timing or duration of the post-reproductive lifespan with females in both ecotypes terminating reproduction before their mid-40s followed by an expected post-reproductive period of ~20 years. Our results highlight the important role of kinship dynamics in the evolution of a long post-reproductive lifespan in long-lived mammals, while further implying that the timing of menopause may be a robust trait that is persistent despite substantial variation in demographic patterns among population.

scholarly journals Beaked and Killer Whales Show How Collective Prey Behaviour Foils Acoustic Predators

2018 ◽  
Author(s):  
Natacha Aguilar de Soto ◽  
Fleur Visser ◽  
Peter Madsen ◽  
Peter Tyack ◽  
Graeme Ruxton ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Killer Whale ◽  
Encounter Rate ◽  
Acoustic Cues ◽  
Killer Whales ◽  
Vocal Behaviour ◽  
Beaked Whales ◽  
Fitness Benefits ◽  
The Cost ◽  
Signal Time

ABSTRACTAnimals aggregate to obtain a range of fitness benefits, but a common cost of aggregation is increased detection by predators. Here we show that, in contrast to visual and chemical signallers, aggregated acoustic signallers need not face higher predator encounter rate. This is the case for prey groups that synchronize vocal behaviour but have negligible signal time-overlap in their vocalizations. Beaked whales tagged with sound and movement loggers exemplify this scenario: they precisely synchronize group vocal and diving activity but produce non-overlapping short acoustic cues. They combine this with acoustic hiding when within reach of eavesdropping predators to effectively annul the cost of aggregation for predation risk from their main predator, the killer whale. We generalize this finding in a mathematical model that predicts the key parameters that social vocal prey, which are widespread across taxa and ecosystems, can use to mitigate detection by eavesdropping predators.

scholarly journals Kinship effects in quasi-social parasitoids I: co-foundress number and relatedness affect suppression of dangerous hosts

2020 ◽  
Vol 130 (4) ◽  
pp. 627-641 ◽  
Author(s):  
Mohamed Khadar Abdi ◽  
Daniela Lupi ◽  
Costanza Jucker ◽  
Ian C W Hardy
Keyword(s):  
Life History ◽  
Public Good ◽  
Inclusive Fitness ◽  
Conflicts Of Interest ◽  
Division Of Labour ◽  
Brood Care ◽  
Social Partners ◽  
History Of ◽  
Fitness Benefits ◽  
Animal Societies

Abstract Explanations for the highest levels of sociality typically invoke the concept of inclusive fitness. Sclerodermus, a genus of parasitoid hymenopterans, is quasi-social, exhibiting cooperative brood care without generational overlap or apparent division of labour. Foundress females successfully co-exploit hosts that are too large to suppress when acting alone and the direct fitness benefits of collective action may explain their cooperation, irrespective of kinship. However, cooperation in animal societies is seldom free of conflicts of interest between social partners, especially when their relatedness, and thus their degree of shared evolutionary interests, is low. We screened components of the life-history of Sclerodermus brevicornis for effects of varying co-foundress number and relatedness on cooperative reproduction. We found that the time taken to paralyse standard-sized hosts is shorter when co-foundress number and/or relatedness is higher. This suggests that, while females must access a paralysed host in order to reproduce, individuals are reluctant to take the risk of host attack unless the benefits will be shared with their kin. We used Hamilton’s rule and prior data from studies that experimentally varied the sizes of hosts presented to congeners to explore how the greater risks and greater benefits of attacking larger hosts could combine with relatedness to determine the sizes of hosts that individuals are selected to attack as a public good. From this, we predict that host size and relatedness will interact to affect the timing of host paralysis; we test this prediction in the accompanying study.

scholarly journals Mapping the adaptive landscape of a major agricultural pathogen reveals evolutionary constraints across heterogeneous environments

2021 ◽  
Author(s):  
Anik Dutta ◽  
Fanny E. Hartmann ◽  
Carolina Sardinha Francisco ◽  
Bruce A. McDonald ◽  
Daniel Croll
Keyword(s):  
Life History ◽  
Large Scale ◽  
Life History Traits ◽  
Genetic Correlations ◽  
Stress Factors ◽  
Life History Trait ◽  
Adaptive Landscape ◽  
Heterogeneous Environments ◽  
Growth Responses ◽  
Trade Offs

AbstractThe adaptive potential of pathogens in novel or heterogeneous environments underpins the risk of disease epidemics. Antagonistic pleiotropy or differential resource allocation among life-history traits can constrain pathogen adaptation. However, we lack understanding of how the genetic architecture of individual traits can generate trade-offs. Here, we report a large-scale study based on 145 global strains of the fungal wheat pathogen Zymoseptoria tritici from four continents. We measured 50 life-history traits, including virulence and reproduction on 12 different wheat hosts and growth responses to several abiotic stressors. To elucidate the genetic basis of adaptation, we used genome-wide association mapping coupled with genetic correlation analyses. We show that most traits are governed by polygenic architectures and are highly heritable suggesting that adaptation proceeds mainly through allele frequency shifts at many loci. We identified negative genetic correlations among traits related to host colonization and survival in stressful environments. Such genetic constraints indicate that pleiotropic effects could limit the pathogen’s ability to cause host damage. In contrast, adaptation to abiotic stress factors was likely facilitated by synergistic pleiotropy. Our study illustrates how comprehensive mapping of life-history trait architectures across diverse environments allows to predict evolutionary trajectories of pathogens confronted with environmental perturbations.

scholarly journals Family feud: permanent group splitting in a highly philopatric mammal, the killer whale (Orcinus orca)

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Eva H. Stredulinsky ◽  
Chris T. Darimont ◽  
Lance Barrett-Lennard ◽  
Graeme M. Ellis ◽  
John K. B. Ford
Keyword(s):  
Killer Whale ◽  
Group Structure ◽  
Group Living ◽  
Orcinus Orca ◽  
Learning Approaches ◽  
Killer Whales ◽  
Internal Factors ◽  
Individual Fitness ◽  
Leadership Experience

Abstract For animals that tend to remain with their natal group rather than individually disperse, group sizes may become too large to benefit individual fitness. In such cases, group splitting (or fission) allows philopatric animals to form more optimal group sizes without sacrificing all familiar social relationships. Although permanent group splitting is observed in many mammals, it occurs relatively infrequently. Here, we use combined generalized modeling and machine learning approaches to provide a comprehensive examination of group splitting in a population of killer whales (Orcinus orca) that occurred over three decades. Fission occurred both along and across maternal lines, where animals dispersed in parallel with their closest maternal kin. Group splitting was more common: (1) in larger natal groups, (2) when the common maternal ancestor was no longer alive, and (3) among groups with greater substructuring. The death of a matriarch did not appear to immediately trigger splitting. Our data suggest intragroup competition for food, leadership experience and kinship are important factors that influence group splitting in this population. Our approach provides a foundation for future studies to examine the dynamics and consequences of matrilineal fission in killer whales and other taxa. Significance statement Group living among mammals often involves long-term social affiliation, strengthened by kinship and cooperative behaviours. As such, changes in group membership may have significant consequences for individuals’ fitness and a population’s genetic structure. Permanent group splitting is a complex and relatively rare phenomenon that has yet to be examined in detail in killer whales. In the context of a growing population, in which offspring of both sexes remain with their mothers for life, we provide the first in-depth examination of group splitting in killer whales, where splitting occurs both along and across maternal lines. We also undertake the first comprehensive assessment of how killer whale intragroup cohesion is influenced by both external and internal factors, including group structure, population and group demography, and resource abundance.

scholarly journals Natural variation in fecundity is correlated with species-wide levels of divergence in Caenorhabditis elegans

2021 ◽  
Author(s):  
Gaotian Zhang ◽  
Jake D Mostad ◽  
Erik C Andersen
Keyword(s):  
Life History ◽  
Caenorhabditis Elegans ◽  
Life History Traits ◽  
Life History Trait ◽  
Selective Sweeps ◽  
C Elegans ◽  
Genome Wide ◽  
Genetic Complexity ◽  
Genomic Regions ◽  
Global Population

Abstract Life history traits underlie the fitness of organisms and are under strong natural selection. A new mutation that positively impacts a life history trait will likely increase in frequency and become fixed in a population (e.g. a selective sweep). The identification of the beneficial alleles that underlie selective sweeps provides insights into the mechanisms that occurred during the evolution of a species. In the global population of Caenorhabditis elegans, we previously identified selective sweeps that have drastically reduced chromosomal-scale genetic diversity in the species. Here, we measured the fecundity of 121 wild C. elegans strains, including many recently isolated divergent strains from the Hawaiian islands and found that strains with larger swept genomic regions have significantly higher fecundity than strains without evidence of the recent selective sweeps. We used genome-wide association (GWA) mapping to identify three quantitative trait loci (QTL) underlying the fecundity variation. Additionally, we mapped previous fecundity data from wild C. elegans strains and C. elegans recombinant inbred advanced intercross lines that were grown in various conditions and detected eight QTL using GWA and linkage mappings. These QTL show the genetic complexity of fecundity across this species. Moreover, the haplotype structure in each GWA QTL region revealed correlations with recent selective sweeps in the C. elegans population. North American and European strains had significantly higher fecundity than most strains from Hawaii, a hypothesized origin of the C. elegans species, suggesting that beneficial alleles that caused increased fecundity could underlie the selective sweeps during the worldwide expansion of C. elegans.

scholarly journals Trinidadian guppies use a social heuristic that can support cooperation among non-kin

2020 ◽  
Vol 287 (1934) ◽  
pp. 20200487 ◽  
Author(s):  
Safi K. Darden ◽  
Richard James ◽  
James M. Cave ◽  
Josefine Bohr Brask ◽  
Darren P. Croft
Keyword(s):  
Poecilia Reticulata ◽  
Social Space ◽  
Inclusive Fitness ◽  
Single Point ◽  
Theoretical Work ◽  
Evolution Of Cooperation ◽  
Social Partner ◽  
Proximate Mechanisms ◽  
Cognitive Limitations ◽  
Fitness Benefits

Cooperation among non-kin is well documented in humans and widespread in non-human animals, but explaining the occurrence of cooperation in the absence of inclusive fitness benefits has proven a significant challenge. Current theoretical explanations converge on a single point: cooperators can prevail when they cluster in social space. However, we know very little about the real-world mechanisms that drive such clustering, particularly in systems where cognitive limitations make it unlikely that mechanisms such as score keeping and reputation are at play. Here, we show that Trinidadian guppies ( Poecilia reticulata ) use a ‘walk away’ strategy, a simple social heuristic by which assortment by cooperativeness can come about among mobile agents. Guppies cooperate during predator inspection and we found that when experiencing defection in this context, individuals prefer to move to a new social environment, despite having no prior information about this new social group. Our results provide evidence in non-human animals that individuals use a simple social partner updating strategy in response to defection, supporting theoretical work applying heuristics to understanding the proximate mechanisms underpinning the evolution of cooperation among non-kin.

Development of intentional stranding hunting techniques in killer whale (Orcinus orca) calves at Crozet Archipelago

1995 ◽  
Vol 73 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Christophe Guinet ◽  
Jérome Bouvier
Keyword(s):  
Growth Curve ◽  
Parental Investment ◽  
Killer Whale ◽  
Elephant Seal ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Juvenile Female ◽  
Adult Females ◽  
Social Transfer ◽  
High Degree

This paper describes the trend in the practice of what we interpret to be the "intentional stranding" hunting technique of two juvenile female killer whales (Orcinus orca), A4 and A5, belonging to pod A on the beaches of Possession Island, Crozet Archipelago. Pod A was composed of three adult females, A2, A3, A6, and one adult male, A1. A2 is A4's mother and A3 is A5's mother. The year of birth and thus the probable age of the two juveniles were estimated from their growth curve determined by means of a photogrammetric technique. These observations indicate that at Crozet Archipelago, juvenile killer whales first practiced intentional stranding on their own when they were 4–5 years old. Their first attempt to capture elephant seal pups by means of this technique was observed when they were 5–6 years old. However, 5- to 6-year-old juveniles still needed the assistance of an adult female to return to the water with their prey. This study indicates that learning hunting techniques needs a high degree of skill and requires high parental investment to reduce the associated risk. Furthermore, social transfer, through apprenticeship, is probably one of the mechanisms that enables the high degree of adaptability observed in killer whales.

scholarly journals Loci, genes, and gene networks associated with life history variation in a model ecological organism,Daphnia pulex(complex)

2018 ◽  
Author(s):  
Jacob W. Malcom ◽  
Thomas E. Juenger ◽  
Mathew A. Leibold
Keyword(s):  
Gene Expression ◽  
Genetic Variation ◽  
Life History ◽  
Molecular Basis ◽  
Life History Traits ◽  
Evolutionary Dynamics ◽  
Daphnia Pulex ◽  
Life History Trait ◽  
Life History Variation ◽  
Trait Variation

ABSTRACTBackgroundIdentifying the molecular basis of heritable variation provides insight into the underlying mechanisms generating phenotypic variation and the evolutionary history of organismal traits. Life history trait variation is of central importance to ecological and evolutionary dynamics, and contemporary genomic tools permit studies of the basis of this variation in non-genetic model organisms. We used high density genotyping, RNA-Seq gene expression assays, and detailed phenotyping of fourteen ecologically important life history traits in a wild-caught panel of 32Daphnia pulexclones to explore the molecular basis of trait variation in a model ecological species.ResultsWe found extensive phenotypic and a range of heritable genetic variation (~0 < H2< 0.44) in the panel, and accordingly identify 75-261 genes—organized in 3-6 coexpression modules—associated with genetic variation in each trait. The trait-related coexpression modules possess well-supported promoter motifs, and in conjunction with marker variation at trans- loci, suggest a relatively small number of important expression regulators. We further identify a candidate genetic network with SNPs in eight known transcriptional regulators, and dozens of differentially expressed genes, associated with life history variation. The gene-trait associations include numerous un-annotated genes, but also support several a priori hypotheses, including an ecdysone-induced protein and several Gene Ontology pathways.ConclusionThe genetic and gene expression architecture ofDaphnialife history traits is complex, and our results provide numerous candidate loci, genes, and coexpression modules to be tested as the molecular mechanisms that underlieDaphniaeco-evolutionary dynamics.

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