Wet soils affect habitat selection of a solitary subterranean rodent (Ctenomys minutus) in a Neotropical region

Abstract

Subterranean rodents are characterized by limited individual mobility and patchy distribution of local populations. Habitat patches where the species is absent may either be unoccupied, but suitable patches, or in fact unsuitable as habitat due to specific habitat features. In the coastal plain of southern Brazil, Ctenomys minutus (Ctenomyidae) inhabits sandy grasslands and dunes. The aim of our study was to analyze the relationship between the distribution of this subterranean rodent and its environment. We considered vegetation and soil features. Our results showed that habitat occupancy patterns of C. minutus are determined by soil moisture and vegetation (food supply), but there might be other habitat features that regulate the habitat choice of this mammal. Habitat discontinuities in the coastal plain of southern Brazil, with numerous barriers to dispersal, are responsible for restricting individuals to their natal areas. This might result in increased intraspecific competition within each population and, consequently, in inbreeding. Os roedores subterrâneos são caracterizados pela baixa mobilidade dos indivíduos e por apresentarem populações distribuídas em manchas de habitat. As manchas em que os indivíduos estão ausentes podem ser locais desocupados, porém que apresentam condições adequadas para a ocupação, ou de fato serem locais inadequados devido a algumas características ambientais específicas. Na planície costeira do sul do Brasil, a espécie Ctenomys minutus (Ctenomyidae) habita regiões de campos arenosos e dunas costeiras. O objetivo do presente estudo foi analisar a relação entre a distribuição deste roedor subterrâneo e o ambiente em que ele habita. Para tal, consideramos características da vegetação e do solo. Nossos resultados demonstraram que o padrão de ocupação de C. minutus é determinado pela umidade do solo e vegetação (recurso alimentar), mas podem existir outras características que regulam a escolha do habitat deste mamífero. As descontinuidades de habitat na planície costeira do sul do Brasil, com inúmeras barreiras para a dispersão da espécie, são responsáveis por restringir os indivíduos as suas áreas natais. Isso pode resultar no aumento da competição intra-específica dentro das populações e, consequentemente, na endogamia.

Can Niche Modeling and Geometric Morphometrics Document Competitive Exclusion in a Pair of Subterranean Rodents (Genus Ctenomys) with Tiny Parapatric Distributions?

“…Both species demonstrate ability to occupy sandy dunes habitat, however, they are not able to co-occur along this habitat: between the two known contact zones, no records of C . minutus was found for over 20 years of studies in areas with sandy dunes 23 , 25 – 27 , 30 , 53 , where C . flamarioni is widely recorded 24 , 29 , 54 (Thales de Freitas personal observations).…”

“…In contrast, C . minutus 23 , 25 – 27 , 30 , 53 is broadly recorded in sandy dunes north of both known contact zones, while C . flamarioni 24 , 29 , 54 has no record in these places.…”

“…Because of the limitations of the ENM-based method, and because experimental studies to test for competitive exclusion often are not feasible, here we also conducted a test for morphological character displacement based on geometric morphometrics data. In addition, we used natural history information for the species, including spatial distribution 23 – 27 , diet composition 28 , and microhabitats requirements 29 , 30 . The combination of both techniques 31 , together with natural history information, can provide stronger, and likely complementary evidence of competitive interactions than the use of any of them alone.…”

Can the environment influence species home‐range size? A case study onCtenomys minutus(Rodentia, Ctenomyidae)

“…Ctenomys sp. (tuco‐tucos) are usually solitary (with some social species) (Lacey, Braude & Wieczorek, 1997; Lacey, Braude & Wierczorek, ; Lacey et al ., ), are typically distributed in small patches of suitable habitats, and have low mobility (Lacey et al ., ; Galiano et al ., ). Species usually use habitats with similar soil characteristics and availability of resources (Lacey et al ., ).…”

“…Species usually use habitats with similar soil characteristics and availability of resources (Lacey et al ., ). However, some species are found in habitats with sharp differences in resource availability and soil characteristics, as is the case for Ctenomys minutus Nehring, 1887 (Galiano, Bernardo‐Silva & Freitas, ; Galiano, Kubiak & Freitas, ; Kubiak, Galiano & Freitas, ; Galiano et al ., ). This species has solitary habits and its distribution is restricted to the coastal plains of southern Brazil, where populations occur along a linear extension of approximately 500 km (Freitas, ; Freygang, Marinho & Freitas, 2004).…”