Short communication Minimum viable population and conservation status of the Atlantic Forest spiny rat Trinomys eliasi Daniel Brito a, *, Marcos de Souza Lima Figueiredo b a Laborato ´rio de Mastozoologia e Manejo de Fauna, Departamento de Zoologia, Instituto de Cie ˆnciasBiolo ´gicas, Universidade Federal de Minas Gerais, Avenida Anto ˆnio Carlos 6627, Pampulha, Belo Horizonte, 31270-901, Minas Gerais, Brazil b Departamento de Zoologia, Instituto de Biologia, CCS, Universidade Federal do Rio de Janeiro, CxP 68044, IlhadoFunda ˜o, Rio de Janeiro, 21941-590, Rio de Janeiro, Brazil Received 3 September 2001; received in revised form 20 August 2002; accepted 1 November 2002 Abstract A population viability analysis (PVA) was conducted to assess the minimum viable population (MVP) of the Atlantic Forest spiny rat Trinomys eliasi, a species threatened by habitat loss and restricted geographical distribution. Objectives were to suggest quasi-extinction thresholds, estimate minimum areas of suitable habitat (MASH) and MVPs, and compare results with the species’ current status. The computer package VORTEX was used. The model predicted sizes of 200 animals to achieve demographic sta- bility, but buffering declines in genetic variability required populations of 2000 animals. Estimated MASHs were approximately 250 and 2500 ha for demographic and genetic stability, respectively. Mortality rate and mean litter size were the most sensitive para- meters to changes in model assumptions. The protection of known populations and the search for extant populations are the first steps in conservation. T. eliasi’s issue could help protecting the coastal shrubland ecosystem of Rio de Janeiro state. Observing IUCN’s criteria for listing threatened species, it is suggested that T. eliasi should be ranked as vulnerable in red lists. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Atlantic Forest; Coastal shrubland; Management; Minimum viable population (MVP); Population viability analysis (PVA); Quasi- extinction; Status; Trinomys; VORTEX 1. Introduction Ongoing species losses are of crisis proportion and on the order of other mass extinction (Jablonski, 1993; Balmford et al., 1998). One of the main goals of con- servation biology is the maintenance of natural systems’ health and diversity—ecosystems, communities, habi- tats, as well as species (Soule´, 1987). The minimum viable population concept (MVP) is an approach that estimates the minimum number of individuals a popu- lation needs in order to be able to persist for a certain period in the future (Shaffer, 1981; Gilpin and Soule´, 1986; Soule´, 1986, 1987). A MVP can be thought of as a set of estimates that are the product of a system in a user-defined time-frame process for estimating criteria for persistence of a species; the process itself is referred to as population viability analysis (PVA) (Soule´, 1987). PVA is a useful and increasingly popular tool (Engen and Sæther, 2000), not only for evaluating the prob- ability of long-term survival of populations, but also for providing useful guidelines for choosing among man- agement options (Boyce, 1992; Lindenmayer et al., 1993; Possingham et al., 1993; Beissinger and Westphal, 1998; Brook et al., 2000). The Brazilian Atlantic Forest, one of the most endangered ecosystems of the world, has been classified as one of the leading five hotspots (Myers et al., 2000), demonstrating its importance for conservation, manage- ment and scientific research. The Atlantic Forest is the most important rodent threatspot in the Neotropics (Amori and Gippoliti, 2001), with four threatened genera (Abrawayaomys, Chaetomys, Phaenomys and Rhagomys) and one potentially threatened genus (Blarinomys), all of them endemic (Amori and Gippoliti, 2001). Our objectives are: (1) to estimate the minimum viable population size for the rodent Trinomys eliasi (Gilpin 0006-3207/03/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0006-3207(02)00344-0 Biological Conservation 112 (2003) 153–158 www.elsevier.com/locate/biocon * Corresponding author. Present address: Rua Andrade Neves 93/ 802, Rio de Janeiro, 20510-230, Rio de Janeiro, Brazil. E-mail address: danielbrito@hotmail.com (D. Brito).