Distribution and Habitat of the Silver Rice Rat, Oryzomys argentatus

Goodyear, Numi C.

doi:10.2307/1381608

Cited by 9 publications

(20 citation statements)

References 5 publications

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“…Since becoming isolated from the mainland $2000 years ago, silver rice rats may have existed at relatively low population densities due to limited food and freshwater resources in the Lower Keys (Goodyear 1987;U.S. Fish and Wildlife Service 1999).…”

Section: Discussionmentioning

confidence: 99%

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Evidence for a recent genetic bottleneck in the endangered Florida Keys silver rice rat (Oryzomys argentatus) revealed by microsatellite DNA analyses

2005

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Low levels of genetic variation are thought to contribute significantly to the higher extinction rates of endemic island populations compared to their mainland counterparts. We used six microsatellite loci to compare the genetic structure of the endangered silver rice rat (Oryzomys argentatus) population in Saddlebunch Key, Florida to the mainland population of the closely related marsh rice rat (Oryzomys palustris natator) in Everglades National Park. Allelic richness and gene diversity are significantly lower in Saddlebunch Key than in the larger mainland population, and the two populations are significantly differentiated as measured by both F-statistics and Bayesian clustering methods. These findings support the classification of the Keys population as a ''distinct vertebrate population'' by the U.S. Fish and Wildlife Service. Current gene diversity (H E ) is higher than expected under mutation-drift equilibrium in Saddlebunch Key, indicating a genetic bottleneck. The Keys population also exhibits a mode shift in its allele frequency distribution which suggests a very recent bottleneck has occurred and is consistent with reports of recent population declines. Although habitat loss and exotic species pose a more immediate and serious threat to silver rice rats, the continued loss of genetic variation may contribute to their long-term extinction risk due to inbreeding or by lowering the population's ability to adapt to future environmental changes. The protection of habitat and the removal of introduced predators and competitors may help increase the population size of silver rice rats and lower their risk of extinction, both from a demographic and a genetic perspective.

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Section: Discussionmentioning

confidence: 99%

“…The silver rice rat occurs at very low densities (<1 individual/ha) in salt marsh and mangrove wetlands on 12 islands in the Lower Keys, but is absent from the Middle and Upper Keys perhaps because of a lack of suitable habitat and freshwater resources (Goodyear 1987;Humphrey 1992; U.S. Fish and Wildlife Service 1999) (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Evidence for a recent genetic bottleneck in the endangered Florida Keys silver rice rat (Oryzomys argentatus) revealed by microsatellite DNA analyses

2005

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“…Also, the apparent absence or very low densities of the rare, endemic silver rice rat Oryzomys palustris natator on islands in the Lower Florida Keys (e.g. Big Pine Key and Boca Chica Key) that contain apparently suitable habitat coincides with the presence of dense populations of R. rattus (Goodyear 1987;Forys et al 1996;Mitchell 2000;Perry 2006). …”

Section: Introduced Rodent Impact On Extant Insular Small Mammals-'comentioning

confidence: 99%

Review of negative effects of introduced rodents on small mammals on islands

Harris

2008

Biol Invasions

119

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In this first comprehensive review of negative effects of introduced rodents on insular small mammals, the focal species Rattus rattus, R. norvegicus, R. exulans and Mus musculus are implicated in at least 11 extinctions. Furthermore, removal experiments, eradication campaigns and control programmes provide evidence for negative effects on extant populations. While data are currently insufficient for meaningful generalisation with regard to the most threatening rodents, the most threatened small mammals, and the true extent of the problem, it is interesting that R. rattus is implicated in the majority of impacts. This may be explained by its extensive distribution and ecological plasticity. I conclude with methodological recommendations to guide data collection for impact quantification and the study of impact mechanism. This information should facilitate the prioritisation and justification of eradication campaigns, control programmes and biosecurity measures while ensuring that much-needed attention is paid to the conservation of insular small mammals.

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“…Studies in Florida have led some researchers to suspect that competition from exotic Rattus raltus and Mus musculus adversely affected populations of endangered native species (Goodyear, 1987;Hersh, 1978;Humphrey and Barbour, 1979;Spitzer, 1983). Exotic rodent species may compete with certain native species (Briese and Smith, 1973;Caldwell and Gentry, 1965;King, 1957;Thornton, 1971;Woods, 1989), and extinctions in oryzomine genera (taxa presently or formerly included in the genus Oryzomys-Honacki et aI" 1982) Megalomys, Nesoryzomys, and Oryzomys have been attributed, all or in part, to the introduction of R. raltus to the Antilles and Galapagos islands (Jackson, 1985;Thornton, 1971;Woods, 1989).…”

mentioning

confidence: 99%

“…Less is known about fine-scale habitat use and resource partitioning in small mammal communities because many species are nocturnal, wide ranging, or otherwise not easily observed. Trapping is the most common technique used to study small mammal communities, but conveys limited information: captured animals passed close enough to a trap to be coaxed in (Douglass, 1989;Goodyear, 1989). Douglass (1989: 651) compared trapping results with directapproach radiotelemetry in Peromyscus maniculatus and concluded that "'microhabitat selection by deer mice determined by live trapping may not reflect true microhabitat selection."…”

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confidence: 99%

Spatial Overlap and Dietary Selection of Native Rice Rats and Exotic Black Rats

Goodyear¹

1992

Journal of Mammalogy

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The silver rice rat (Oryzomys argentatus), a rare endemic rodent, and the black rat (Rattus rattus), an exotic species, have coexisted for <500 years in the Florida Keys. Determination of fine8 scale movements and behavior, by use of neck-attached fluorescent dust dispensers, revealed the degree of overlap in use of space, and some food resources, in free-ranging animals. Food selection tests were conducted in the laboratory. Significant differences in vegetation association, behavior, arboreality, and diet were found. From estimates of spatial niche overlap based on four indices I suggested the differences were biologically insignificant; the average value of four estimators on the habitat-choice resource axis was 89%, higher than reported for 47 of 48 pair-wise comparisons of native rodent species. I suggest that silver rice rat populations may be jeopardized by the presence of black rats whose invasion was reported to have caused oryzomine extinctions in the Galapagos and Antilles islands.

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Distribution and Habitat of the Silver Rice Rat, Oryzomys argentatus

Cited by 9 publications

References 5 publications

Evidence for a recent genetic bottleneck in the endangered Florida Keys silver rice rat (Oryzomys argentatus) revealed by microsatellite DNA analyses

Evidence for a recent genetic bottleneck in the endangered Florida Keys silver rice rat (Oryzomys argentatus) revealed by microsatellite DNA analyses

Review of negative effects of introduced rodents on small mammals on islands

Spatial Overlap and Dietary Selection of Native Rice Rats and Exotic Black Rats

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