hyena relatives

Introduction

Hyenas, belonging to the family Hyaenidae, are fascinating carnivores known for their diverse ecological roles and complex social structures. Despite having only four extant species, hyenas exhibit a wide range of behaviors and adaptations that have intrigued researchers. This synthesis explores the relatedness and social behaviors of hyenas, focusing on the spotted hyena (Crocuta crocuta), brown hyena (Parahyaena brunnea), and striped hyena (Hyaena hyaena).

Key Insights

Social Structure and Relatedness in Spotted Hyenas:
- Spotted hyenas live in large, complex social groups called clans, which resemble primate societies in their hierarchical structure and social interactions .
- Within clans, relatedness is higher within matrilines, and cooperation often occurs among unrelated clan-mates, suggesting direct fitness benefits from group living .
- Spotted hyenas can discriminate among various types of siblings, favoring full-sibling littermates over half-siblings, which aligns with kin selection theory.
Social Behavior and Relatedness in Brown Hyenas:
- Brown hyenas exhibit helping behavior influenced by relatedness, with females provisioning young even if distantly related, while males show more selective provisioning.
- Despite low genetic diversity due to a long-term decline in population size, brown hyenas maintain distinct subpopulations with no evidence of inbreeding in captive individuals.
Social Complexity in Striped Hyenas:
- Striped hyenas, typically solitary, form polyandrous groups with complex patterns of relatedness, where males within groups are often close relatives, but male-female pairs are usually unrelated.
- Different populations of striped hyenas exhibit behavioral plasticity, with social tolerance and cooperation among females increasing in areas with higher prey density.
Genetic and Evolutionary Insights:
- The striped hyena's genome shows adaptations to a scavenging lifestyle, with expansions in immune and digestive system-related genes, aiding in pathogen resistance and carrion digestion.
- Ancient mitochondrial genomes from cave hyenas provide insights into the evolutionary history of the genus Crocuta, showing higher genetic diversity in extinct cave hyenas compared to extant species.

Conclusion

Hyenas exhibit a remarkable range of social structures and behaviors influenced by relatedness and ecological conditions. Spotted hyenas form complex, cooperative clans with intricate kin discrimination, while brown hyenas show selective helping behavior based on relatedness. Striped hyenas, though generally solitary, display social flexibility depending on resource availability. Genetic studies reveal adaptations to their respective lifestyles and provide a deeper understanding of their evolutionary history. These insights highlight the adaptive strategies that have enabled hyenas to thrive in diverse environments.

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.

Hyena societies

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

Extended and Continuous Decline in Effective Population Size Results in Low Genomic Diversity in the World’s Rarest Hyena Species, the Brown Hyena

Brown hyenas have extremely low genetic diversity, likely due to a continuous decline in population size since the Pleistocene, with potential subpopulations within the species.

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.

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.

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.

Kin discrimination in the spotted hyena (Crocuta crocuta): nepotism among siblings

Spotted hyenas can distinguish between various types of siblings, using familiarity-based cues and phenotype matching mechanisms to recognize kin.

Genetic relatedness and space use in two populations of striped hyenas (Hyaena hyaena)

Higher per capita prey density in striped hyena populations leads to relaxed competition for food, greater social tolerance, and den sharing among females.

Ancient mitochondrial genomes from Chinese cave hyenas provide insights into the evolutionary history of the genus Crocuta

Chinese cave hyena fossils show a deep divergence in mitochondrial lineage, suggesting a split from European and African relatives about 1.85 million years ago.

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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