Population and habitat characteristics of two sympatric species of Ctenomys (Rodentia: Octodontidae)

Malizia, Ana I.; Vassallo, Aldo Iván; Busch, Cristina

doi:10.4098/at.arch.91-5

Cited by 50 publications

(35 citation statements)

References 7 publications

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“…At this locality, these species co‐occur in coastal habitats that are characterized by sandy soils and that are dominated by grasses and herbaceous plants. Although the study species occur in sympatry, they occupy slightly different habitats; although C. australis is restricted to sand dunes characterized by minimal vegetative cover, C. talarum inhabits more heavily vegetated inter‐dune areas and adjacent coastal grasslands (Malizia, Vassallo & Busch, 1991).…”

Section: Methodsmentioning

confidence: 99%

Effects of contrasting demographic histories on selection at major histocompatibility complex loci in two sympatric species of tuco-tucos (Rodentia: Ctenomyidae)

Cutrera

Lacey

Mora

et al. 2010

Biological Journal of the Linnean Society

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To explore the impact of history on selection and genetic structure at functional loci, we compared patterns of major histocompatibility complex (MHC) variability in two sympatric species of ctenomyid rodents with different demographic backgrounds. Although Ctenomys talarum has experienced a stable demographic history, Ctenomys australis has undergone a recent demographic expansion. Accordingly, we predicted that MHC allele frequency distributions should be more skewed, differences between coding and noncoding regions should be less pronounced, and evidence of current selection on MHC loci should be reduced in C. australis relative to C. talarum. To test these predictions, we compared variation at the MHC class II DRB and DQA genes with that at multiple neutral markers, including DQA intron 2, the mitochondrial control region, and 8-12 microsatellite loci. These analyses supported the first two of our predictions but indicated that estimates of selection (based on w-values) were greater for C. australis. Further exploration of these data, however, revealed differences in the time frames over which selection appears to have acted on each species, with evidence of contemporary selection on MHC loci being limited to C. talarum. Collectively, these findings indicate that demographic history can substantially influence genetic structure at functional loci and that the effects of history on selection may be temporally complex and dynamic.

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Section: Methodsmentioning

confidence: 99%

Effects of contrasting demographic histories on selection at major histocompatibility complex loci in two sympatric species of tuco-tucos (Rodentia: Ctenomyidae)

Cutrera

Lacey

Mora

et al. 2010

Biological Journal of the Linnean Society

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“…It is worth noting that, although most species of Ctenomys show disjunct distributions, the population here studied shares its geographic range with C. australis, constituting a rare case of sympatry (Contreras & Reig, 1965;Malizia, Vassallo & Busch, 1991).…”

Section: Introductionmentioning

confidence: 92%

Population dynamics of the fossorial rodent Ctenomys talarum (Rodentia: Octodontidae)

Malizia

1998

Journal of Zoology

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As part of a study on the ecological strategies related to adaptation to the subterranean habitat of genus Ctenomys (tuco-tucos), a natural population of C. talarum was live-trapped at Necochea (Buenos Aires Province, Argentina) with the aim of providing information on its population ecology. Population size was consistently low throughout the study and was related to the low habitat productivity. Mortality rates were low, although for juveniles the estimations were higher than for adults. Individuals have an average life expectancy of 22±25 months, but some individuals lived at least three years. Reproductive activity started by July and ended by March, when last known pregnancies were recorded. This long reproductive season allowed a gradual incorporation of young over an extended period of time, with a restricted period of recruitment lacking. Sex ratio did not depart from 1:1 and appears to be density dependent. The spatial distribution of individuals was clumped and corresponded to the patchy distribution of suitable habitats. The results are compared and contrasted with those from previous demographic studies performed in other conspeci®cs as well as in other subterranean rodents.

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“…Busch (1989) showed that C. australis thermoregulated better than C. talarum in cold and warm environments and also maintained a higher body temperature: limited thermoregulation occurred in C. talarum when it was colder than 20 8C but C. australis maintained body temperature down to 10 8C. It is therefore evident that the pattern of habitat segregation and soil utilization by the two species (Malizia et al, 1991;Comparatore et al, 1992) does not depend only on the morphological traits associated with digging. On the other hand, C. talarum and C. australis are very different in fur colour and body size.…”

Section: Integrating Morphological Physiological and Ecological Datamentioning

confidence: 98%

“…Figure 1 provides for both species a phylogenetic and geographical context. Previous work has shown the existence of a pattern of habitat segregation, according to soil and vegetation types, that characterizes the microspatial distribution of both species (Malizia, Vassallo & Busch, 1991;Comparatore, Agnudsdei & Busch, 1992). Previous work has shown the existence of a pattern of habitat segregation, according to soil and vegetation types, that characterizes the microspatial distribution of both species (Malizia, Vassallo & Busch, 1991;Comparatore, Agnudsdei & Busch, 1992).…”

Section: Introductionmentioning

confidence: 99%

Functional morphology, comparative behaviour, and adaptation in two sympatric subterranean rodents genus Ctenomys (Caviomorpha: Octodontidae)

1998

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Two species of tuco-tucos, Ctenomys talarum and C. australis, overlap geographically in south-eastern Buenos Aires Province, Argentina. C. talarum (100±180 g) occupies habitats with clayey and harder soils, while the larger C. australis (300±600 g) occupies sandy and quite friable soils. This study compares the digging apparatus and digging performance of both species, and also provides additional ecological data to describe the adaptations of both species. When confronted with sandy, friable soils, both tuco-tucos exclusively use their forelimbs (`scratch digging' mode) to break the soil. When confronted with harder and clayey soils, C. australis used its forelimbs and, less frequently, its incisors, but no appreciable effectiveness was observed in breaking the soil. On the other hand, C. talarum behaved as a`scratch' and`chisel-tooth digger' species, using both forelimbs and incisors to dig tunnels in extremely hard soils. C. talarum showed relatively larger forelimb extensors than C. australis. Moreover, I hypothesize that the structure of the ulna in C. talarum may increase the effective forces of the digital and carpal¯exors, thus accounting for the enhanced digging ability in this species. Outward forces exerted by the distal elements (claws-digits-carpals) when forelimbs impact the soil appear to be a critical factor in loosening soil fragments. In addition, the increased upper incisor procumbency of C. talarum correlated with an effective chisel-tooth digging behaviour. Finally, I brie¯y examine phylogenetic and biogeographical factors that may account for some C. australis morphological and physiological traits. It is suggested that the digging ability of C. australis could be a by-product of its larger size, a likely adaptation to evade predation.

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Population and habitat characteristics of two sympatric species of Ctenomys (Rodentia: Octodontidae)

Cited by 50 publications

References 7 publications

Effects of contrasting demographic histories on selection at major histocompatibility complex loci in two sympatric species of tuco-tucos (Rodentia: Ctenomyidae)

Effects of contrasting demographic histories on selection at major histocompatibility complex loci in two sympatric species of tuco-tucos (Rodentia: Ctenomyidae)

Population dynamics of the fossorial rodent Ctenomys talarum (Rodentia: Octodontidae)

Functional morphology, comparative behaviour, and adaptation in two sympatric subterranean rodents genus Ctenomys (Caviomorpha: Octodontidae)

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