Ecological constraints drive social evolution in the African mole–rats

Faulkes, Chris G.; Bennett, Nigel C.; Bruford, Michael William; O'Brien, H. P.; Aguilar, G. H.; Jarvis, Jennifer U. M.

doi:10.1098/rspb.1997.0226

Cited by 244 publications

(231 citation statements)

References 33 publications

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“…Hazell et al, 2000;Greeff and Bennett, 2000;Burland et al, 2002Burland et al, , 2004Barnett et al, 2003;Ganem and Bennett, 2004). It may be expected that, in addition to the confamiliar naked molerat (Heterocephalus glaber), this group of African mole-rats will be of particular interest for gerontological research, taking into account longevity quotients similar to those of humans (Buffenstein, 2005;Dammann and Burda, 2006) combined with the differential levels of chromosomal and mitochondrial DNA sequence divergence, which is emphasized by the sequences available to date (Faulkes et al, 1997Ingram et al, 2004; this paper).…”

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confidence: 94%

Cytochrome b sequence analysis reveals differential molecular evolution in African mole-rats of the chromosomally hyperdiverse genus Fukomys (Bathyergidae, Rodentia) from the Zambezian region

Daele

Verheyen

Brunain

et al. 2007

Molecular Phylogenetics and Evolution

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African mole-rats (Bathyergidae, Rodentia) of the (eu)social genus Fukomys are one of the most speciose mammal genera endemic to Sub-Saharan Africa. Fukomys distributed in the Zambezian phytochorion is characterized by extreme chromosomal variation (2n = 40-78). We inferred a molecular phylogeny of Zambezian Fukomys to resolve the interrelationships and the evolutionary history of the known chromosomal races. We sequenced the entire cytochrome b gene (1140 bp) for a total of 66 specimens representing 18 karyotypical races from Zambia. An additional 31 sequences were retrieved from GenBank including data on all other chromosomal races. The haplotypes belonging to a small chromosomal race from Salujinga cluster with the Fukomys mechowii (Giant mole-rat) haplotypes. Differential degrees of chromosomal variation are observed among the major mole-rat clades, which is most pertinent when comparing the central Zambezian Fukomys micklemi and the northern Zambezian Fukomys whytei clades. The karyotypically hyper-diverse (12 known chromosomal races) Fukomys micklemi clade shows low levels of cytochrome b sequence divergence. Within the F. whytei clade we find a more conservative pattern of chromosomal diversification (three known chromosomal races) while the levels of sequence divergence are much higher then in the F. micklemi clade. Our results suggest that chromosomal changes may drive phyletic divergence and, eventually, speciation. The observed cladogenetic events during the Plio-Pleistocene within the F. mechowii, F. whytei, F. damarensis and F. micklemi clades appear to coincide with climatically mediated speciation bursts in other savannah dwelling mammals, including hominids. Based on the molecular data presented, combined with morphological and chromosomal data, the taxonomic implication seems to be that Fukomys may contain several (undescribed) cryptic species.

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confidence: 94%

Cytochrome b sequence analysis reveals differential molecular evolution in African mole-rats of the chromosomally hyperdiverse genus Fukomys (Bathyergidae, Rodentia) from the Zambezian region

Daele

Verheyen

Brunain

et al. 2007

Molecular Phylogenetics and Evolution

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“…Damaraland mole-rats live in the deserts of southern Africa, where for much of the year the compacted-sand substrate through which they dig their foraging and dispersal tunnels is extremely costly to work (Lovegrove 1989); an ecological constraint that is thought to have favored the evolution of delayed dispersal Jarvis et al 1994;Faulkes et al 1997). This constraint relaxes markedly, however, during periods of sustained rainfall, which soften the sands and stimulate prolific excavation and dispersal by subordinates of both sexes (to either found new colonies or, among males, to seek matings or immigration opportunities in other groups; Jarvis and Bennett 1993;Hazell et al 2000;Burland et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Physiological suppression eases in Damaraland mole-rat societies when ecological constraints on dispersal are relaxed

Young

Oosthuizen

Lutermann

et al. 2010

Hormones and Behavior

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In many vertebrate societies, subordinate females exhibit down-regulated reproductive physiologies relative to those of dominants, a condition commonly termed physiological suppression. Research into the causes of physiological suppression has focused principally on the role of the subordinate's social environment (typically the presence of the dominant female and/or an absence of unrelated males within the group), while few studies have considered the additional role that the physical environment may play. Here we present new evidence from wild Damaraland mole-rats, Fukomys damarensis, revealing that physiological suppression among subordinate females eases markedly during the annual rains (a time when ecological constraints on dispersal are relaxed), despite the continued presence of the dominant female and in groups that contain no new immigrant males. Subordinate females showed substantially higher pituitary sensitivities to GnRH challenge during the wet period than the dry, a contrast that cannot be attributed to between-female differences (as it holds for paired within-female comparisons), associated changes in body mass (as our analyses control for this), or concomitant reductions in physiological stress (as their urinary cortisol concentrations were actually higher in the wet period). We suggest that our findings reflect selection for the maintenance of reproductive readiness among subordinate females during high rainfall periods, given the increased likelihood of encountering dispersal and/or mating opportunities with extra-group males when ecological constraints on dispersal are relaxed.These findings reveal new complexity in the processes that regulate physiological suppression, suggesting a key role in some species for changes in the physical as well as social environment.

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“…A similar explanation has been offered for sociality in vertebrates threatened by harsh environments with unpredictable food supply. In both naked mole-rats (Faulkes et al 1997) and certain cooperatively breeding bird families (Rubenstein & Lovette 2007), phylogenetically controlled comparative analyses identified significant associations between sociality and unpredictable environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

Kin structure, ecology and the evolution of social organization in shrimp: a comparative analysis

2009

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Eusocial societies present a Darwinian paradox, yet they have evolved independently in insects, mole-rats and symbiotic shrimp. Historically, eusociality has been thought to arise as a response to ecological challenges, mediated by kin selection, but the role of kin selection has recently been questioned. Here we use phylogenetically independent contrasts to test the association of eusociality with ecological performance and genetic structure (via life history) among 20 species of sponge-dwelling shrimp (Synalpheus) in Belize. Consistent with hypotheses that cooperative groups enjoy an advantage in challenging habitats, we show that eusocial species are more abundant, occupy more sponges and have broader host ranges than nonsocial sister species, and that these patterns are robust to correction for the generally smaller body sizes of eusocial species. In contrast, body size explains less or no variation after accounting for sociality. Despite strong ecological pressures on most sponge-dwellers, however, eusociality arose only in species with non-dispersing larvae, which form family groups subject to kin selection. Thus, superior ability to hold valuable resources may favour eusociality in shrimp but close genetic relatedness is nevertheless key to its origin, as in other eusocial animals.

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Ecological constraints drive social evolution in the African mole–rats

Cited by 244 publications

References 33 publications

Cytochrome b sequence analysis reveals differential molecular evolution in African mole-rats of the chromosomally hyperdiverse genus Fukomys (Bathyergidae, Rodentia) from the Zambezian region

Cytochrome b sequence analysis reveals differential molecular evolution in African mole-rats of the chromosomally hyperdiverse genus Fukomys (Bathyergidae, Rodentia) from the Zambezian region

Physiological suppression eases in Damaraland mole-rat societies when ecological constraints on dispersal are relaxed

Kin structure, ecology and the evolution of social organization in shrimp: a comparative analysis

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