The role of chromosome variation in the speciation of the red brocket deer complex: the study of reproductive isolation in females

Abstract

BackgroundThe red brocket deer, Mazama americana, has at least six distinct karyotypes in different regions of South America that suggest the existence of various species that are today all referred to as M. americana. From an evolutionary perspective, the red brockets are a relatively recent clade that has gone through intense diversification. This study sought to prove the existence of post-zygotic reproductive isolation in deer offspring between distinct chromosome lineages. To achieve this, inter-cytotype and intra-cytotype crosses were performed, which resulted in both F1 hybrid (n = 5) and pure offspring (n = 3) in captivity.ResultsF1 females were analyzed in terms of their karyotypes, ovarian histology, estrous cycles and in vitro embryo production. Pure females presented parameters that were similar to those previously reported for M. Americana; however, the parameters for hybrid females were different. Two hybrids were determined to be sterile, while the remaining hybrids presented characteristics of subfertility.ConclusionsThe results support the existence of well-established reproductive isolation among the most distant karyotype lineages and elucidates the need to define all karyotype variants and their geographical ranges in order to define the number of species of red brocket.

Using sperm morphometry and multivariate analysis to differentiate species of gray Mazama

“…The genus Mazama , is known to be the most complex [1,2] and is separated into two clades, the gray ( M. gouazoubira and M. nemorivaga ) and the red Mazama ( M. americana, M. bororo and M. nana ) [3]. In the red clade, the species M. americana has recently been considered a complex of cryptic species, because different cytotypes exist in different regions of Brazil [4] and different degrees of reproductive isolation exist between these cytotypes [5]. Regarding the gray clade, phylogenetic analyses based on mtDNA, cytochrome b (Cyt b ) and cytochrome c oxidase subunit II (COX II) have shown significant genetic differences, not only between red and gray Mazama , but also between M. gouazoubira and M. nemorivaga , and even among individuals within the species studied [3,6,7].…”

Intrapopulation Chromosomal Polymorphism in <b><i>Mazama gouazoubira</i></b> (Cetartiodactyla; Cervidae): The Emergence of a New Species?

“…However, heterozygotes for a single centric fusion generally form trivalents in meiosis, causing minimal problems in reproduction [Baker and Bickham, 1986], as observed in a meiotic study performed on M. americana [Aquino et al, 2013]. However, Cursino et al [2014] and Salviano et al [2017] verified that hybrids of different M. americana cytotypes possess a mechanism of post-zygotic reproductive isolation that involves subfertility or infertility, demonstrating reproductive isolation with the accumulation of chromosomal rearrangements. When accumulated fixation of several centric fusions occurs, reproductive isolation is increasingly likely due to gamete incompatibility [Dobigny et al, 2002].…”

Biomechanical evaluation of spring system for implant-supported prosthesis: analysis by photoelasticity and extensometry

“…The red brocket deer (Mazama americana) is one of the best examples for a large mammal of karyotypic diversification leading to true sympatric speciation (see Amato et al, 2000, andHuang et al, 2006, for a similar case in Muntiacus reevesi). Members of this species complex (Abril et al, 2010;Aquino et al, 2013;Cursino et al, 2014), currently occur in forest habitats (Bodmer, 1997;Duarte, 1996;Escobedo-Morales et al, 2016;Varela et al, 2010) throughout a wide distribution range from México to the north of Argentina (Eisemberg, 1989;Emmons, 1990). Earlier studies described up to eight different species within the red brocket deer complex (Allen, 1915) that were later included in one with a variable number (9-15) of subspecies (Cabrera, 1960;Czernay, 1987;Rossi, 2000).…”

“…Members of this species complex (Abril et al, 2010;Aquino et al, 2013;Cursino et al, 2014), currently occur in forest habitats (Bodmer, 1997;Duarte, 1996;Escobedo-Morales et al, 2016;Varela et al, 2010) throughout a wide distribution range from México to the north of Argentina (Eisemberg, 1989;Emmons, 1990). Earlier studies described up to eight different species within the red brocket deer complex (Allen, 1915) that were later included in one with a variable number (9-15) of subspecies (Cabrera, 1960;Czernay, 1987;Rossi, 2000). A cryptic species, the small red brocket deer M. bororo, was initially included within the complex but lately identified as a separated species based on chromosomal and morphological differences (Duarte, 1996;Duarte and Merino, 1997;Duarte and Jorge, 2003).…”

“…The analysis of the cytogenetic evolution has recently shown the existence of two karyotypic lineages that evolved from a common ancestor by chromosomal rearrangements: Lineage A, which includes the Rondônia and Juína karyotypes; and Lineage B, which includes the Jarí, Carajás, Santarém, and Paraná karyotypes (Abril et al, 2010). Both lineages are also well differentiated at the level of mtDNA (Abril et al, 2010) and maintain reproductive isolation, with hybrids showing sterility or subfertility (Aquino et al, 2013;Cursino et al, 2014;Salviano et al, 2017). All these results clearly point to the existence of at least two separate species within the current Mazama americana specific nomination, which need to be formally described, and probably a deeper investigation could reveal further subdivisions under an ongoing process of rapid sympatric speciation based on chromosomal rearrangements (Abril et al, 2010).…”