what are hyenas related to

Introduction

Hyenas are fascinating carnivores known for their complex social structures and diverse ecological roles. The family Hyaenidae includes four extant species: the spotted hyena (Crocuta crocuta), the brown hyena (Parahyaena brunnea), the striped hyena (Hyaena hyaena), and the aardwolf (Proteles cristata). This synthesis explores the evolutionary relationships, social behaviors, and ecological adaptations of hyenas.

Key Insights

Evolutionary Relationships and Origins
- Spotted hyenas are closely related to extinct Late Pleistocene cave hyenas from Europe and Asia, with evidence suggesting multiple migrations out of Africa between 3.5 and 0.35 million years ago .
- The genus Crocuta, which includes both African spotted and Eurasian cave hyenas, shows a deep divergence (~2.5 million years ago) between African and Eurasian populations, with evidence of bidirectional gene flow after the lineages split.
Social Structures and Relatedness
- Spotted hyenas live in complex social groups called clans, which resemble the social structures of cercopithecine primates like baboons and macaques. These clans are characterized by female philopatry, male dispersal, and hierarchical structures .
- Within clans, relatedness is higher within matrilines than among them, and cooperation often occurs among unrelated clan-mates against close paternal kin in other clans .
- Striped hyenas, although behaviorally solitary, form polyandrous spatial groups with patterns of relatedness indicating that male coalitions are not strictly due to philopatry or dispersal with relatives.
Ecological Adaptations
- The striped hyena's genome shows significant expansions in immune and digestive system-related gene families, likely as an adaptive response to its scavenging lifestyle. This includes positive selection in genes related to immune defense and digestive processes.
- Brown hyenas exhibit helping behavior influenced by relatedness, with females provisioning young as distantly related as second cousins, while males provision only half-sibs.
Historical and Fossil Evidence
- The fossil record indicates that hyenas were once a diverse group with over 80 species, peaking in diversity during the Late Miocene. Modern hyenas are the remnants of this once large and diverse family .
- Analysis of a late Pleistocene micromammal assemblage suggests that ancient spotted hyenas preyed upon small rodents, a behavior rarely observed in modern hyenas.

Conclusion

Hyenas exhibit a rich tapestry of evolutionary history, social complexity, and ecological diversity. Spotted hyenas share a close evolutionary relationship with extinct cave hyenas and display complex social structures similar to those of some primates. Striped hyenas have adapted to a scavenging lifestyle through significant genetic changes. The fossil record and historical data provide insights into the once diverse and widespread nature of the Hyaenidae family. Overall, hyenas are a remarkable example of adaptive evolution and social complexity among carnivores.

What are hyenas related to

Summary

Introduction

Key Insights

Conclusion

Sources and full results

Behavioural structuring of relatedness in the spotted hyena (Crocuta crocuta) suggests direct fitness benefits of clan‐level cooperation

Spotted hyenas derive large net fitness benefits from clan-level cooperation, with low mean relatedness within clans suggesting they cooperate with unrelated clan-mates against close paternal kin in other clans.

Society, demography and genetic structure in the spotted hyena

Spotted hyenas maintain strong social relationships with kin year-round, despite resource limitations, despite differences in social structure and resource access.

Pleistocene Chinese cave hyenas and the recent Eurasian history of the spotted hyena, Crocuta crocuta

Spotted hyenas originated from a widespread Eurasian population in the Late Pleistocene, with their recent history suggesting a recent migration out of Africa.

Patterns of relatedness and parentage in an asocial, polyandrous striped hyena population

Striped hyenas form polyandrous spatial groups with mixed relatedness, suggesting selection to reduce inbreeding and competition among relatives for resources and mates.

Helping behaviour in brown hyenas

Brown hyenas show asymmetries in helping behavior among clan members, with females providing young as distantly related as second cousins, and males providing half sibs but not cousins.

Hyena societies

Hyenas exhibit ecological and social diversity, occupying diverse habitats and filling specialized niches, with four living species in the family Hyaenidae.

Hyena as a predator of small mammals? Taphonomic analysis from the site of Bois Roche, France

Hyenas in the late Pleistocene ate small rodents, a feeding habit rarely observed today, likely due to local abundance of prey species due to rodent population outbreaks.

Hyena paleogenomes reveal a complex evolutionary history of cross-continental gene flow between spotted and cave hyena

Hyena paleogenomes reveal a complex evolutionary history with bidirectional gene flow between African and Eurasian Crocuta lineages, suggesting a deep divergence and potential adaptive advantages from admixture.

Social Facilitation, Affiliation, and Dominance in the Social Life of Spotted Hyenas a

Spotted hyenas balance cooperation and competition within their social life, with individual differences in cooperation and competition emerging from a general tendency to do-what-other-hyenas-are-doing.

Genome-Wide Analyses Provide Insights into the Scavenging Lifestyle of the Striped Hyena (Hyaena hyaena).

The striped hyena's immune and digestive system-related gene families have significantly expanded, likely as an adaptive response to its scavenging lifestyle.

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