First records of pigmentation anomalies in the marsh deer at its southernmost stronghold: a warning message?

Abstract

Pigmentation anomalies (e.g., albinism, leucism) in Neotropical mammals are considered rare. Identifying the spatiotemporal distribution and prevalence of pigmentation anomalies is important to better assess the evolutionary basis of color variation. The southernmost population of the marsh deer (Blastocerus dichotomus) occurs within a relatively small area (< 2700 km²) of the Delta of the Paraná River, being fragmented into three subpopulations with low gene flow among them. Typically, the marsh deer has a brownish red to bright rufous chestnut-colored coat; at least two albino individuals have been reported in other populations of the species, but other anomalous colorations (i.e., leucism) have not been described for this species. Here, we present seven records of leucistic marsh deer from the Delta of the Paraná River, with the coloration of these individuals showing different levels of contrast from typically pigmented conspecifics. The presence of the leucistic phenotype in this population could be the product of its high level of homozygosis, but further studies are needed to confirm this relationship. Since the observed leucistic individuals were adults and apparently of breeding age, the possible maladaptive condition of this phenotype in this population remains to be evaluated.

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European Journal of Wildlife Research (2023) 69:59
https://doi.org/10.1007/s10344-023-01694-y
RESEARCH
First records ofpigmentation anomalies inthemarsh deer atits
southernmost stronghold: awarning message?
JavierA.Pereira1 · LauraI.Wolfenson2 · DiegoF.Artero3 · EstebanC.Argerich4· DiegoVarela5·
NataliaG.Fracassi6
Received: 13 October 2022 / Revised: 3 May 2023 / Accepted: 16 May 2023 / Published online: 23 May 2023
© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023
Abstract
Pigmentation anomalies (e.g., albinism, leucism) in Neotropical mammals are considered rare. Identifying the spatiotemporal
distribution and prevalence of pigmentation anomalies is important to better assess the evolutionary basis of color variation.
The southernmost population of the marsh deer (Blastocerus dichotomus) occurs within a relatively small area (< 2700 km2)
of the Delta of the Paraná River, being fragmented into three subpopulations with low gene flow among them. Typically, the
marsh deer has a brownish red to bright rufous chestnut-colored coat; at least two albino individuals have been reported in
other populations of the species, but other anomalous colorations (i.e., leucism) have not been described for this species. Here,
we present seven records of leucistic marsh deer from the Delta of the Paraná River, with the coloration of these individuals
showing different levels of contrast from typically pigmented conspecifics. The presence of the leucistic phenotype in this
population could be the product of its high level of homozygosis, but further studies are needed to confirm this relationship.
Since the observed leucistic individuals were adults and apparently of breeding age, the possible maladaptive condition of
this phenotype in this population remains to be evaluated.
Keywords Blastocerus dichotomus· Delta of the Paraná River· Genetic diversity· Leucism· Phenotype
Introduction
Variation in color patterns is a conspicuous phenotypic trait in
mammals (Hofreiter and Schöneberg 2010; Caro etal. 2017;
Eizirik and Trindade 2021). Skin, hair, and eye pigmentation
in mammals is defined by the quantity, quality, and distribution
of two types of melanin pigments: eumelanin (i.e., insoluble
brown to black pigments) and pheomelanin (i.e., alkali-soluble
yellow to reddish-brown pigments), which are synthesized by
melanocytes (Ito and Wakamatsu 2008). Processes altering the
synthesis, distribution, and aggregation of melanin can lead to
pigmentation anomalies including albinism (i.e., total absence
of coloration in the whole body and red or pink eyes) and leu-
cism (i.e., total or partial absence of pigmentation except for
the eyes and/or extremities which remain with dark or blue pig-
mentation) (Miller 2005; Acevedo and Aguayo 2008; Fertl and
Rosel 2009). Albinism is a genetic condition caused by muta-
tions in several different genes (Summers 2009), while leucism
can be attributed to homozygosity for recessive alleles in one
or more genes (Owen and Shimmings 1992; Cruickshank and
Robinson 1997). The incidence of pigmentation anomalies
has been related to natural populations that occur on islands
* Javier A. Pereira
jpereira@conicet.gov.ar
1 División Mastozoología, Museo Argentino de Ciencias
Naturales “Bernardino Rivadavia” – Consejo Nacional
de Investigaciones Científicas y Técnicas (CONICET),
Av. Ángel Gallardo 470, 1405CiudaddeBuenosAires,
Argentina
2 División Mastozoología, Museo Argentino de Ciencias
Naturales “Bernardino Rivadavia” – Consejo Nacional
de Investigaciones Científicas y Técnicas (CONICET),
CiudaddeBuenosAires, Argentina
3 Arauco Argentina S.A, CiudaddeBuenosAires, Argentina
4 Asociación Argentina de Fotógrafos de Naturaleza
(AFONA), ProvinciadeBuenosAires, Argentina
5 Instituto de Biología Subtropical, Universidad Nacional
de Misiones – Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET) andAsociación Civil
Centro de Investigaciones del Bosque Atlántico (CeIBA),
PuertoIguazú,Misiones, Argentina
6 Estación Experimental Agropecuaria Delta del Paraná,
Instituto Nacional de Tecnología Agropecuaria (INTA),
Provincia de Buenos Aires, Campana, Argentina
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