Comparative embryogenesis in ungulate domesticated species

Abstract

We compared embryogenesis of five species of domesticated even‐toed and one odd‐toed ungulate and used a phylogenetic framework to contextualize such comparison. Organ systems that occur relatively earlier in embryogenesis generally have more time to develop and therefore are found to be more mature at birth when compared to structures that appear later in development. We hypothesized that the less mature the animals' organs are at birth, the more they are susceptible to artificial selection. The horse had the most mature organs at birth, followed by cattle, reindeer, sheep/goat, and pig. This pattern of maturity could be observed almost during the entire development. Heterochronic shifts among species were observed only after fur starts to develop. Changes in the fur coloration are one of the first observable signs of domestication and the heterochrony of this trait may be related to the effects on neural crest‐derived pigment cells by artificial selection. The six ungulate species also differ in the relative duration of their weaning period and the potential extent of its artificial shortening. We put all these traits in the context of their inherited evolutionary characteristics and artificial domestication process. Related to their altriciality, carnivoran domesticates, which also belong to Scrotifera, are less mature at birth than all domesticated ungulates. Although we detected clear character correlations to life history traits, it is impossible based on the present data, to trace specific exaptations to the domestication process. We hypothesize a deep time developmental penetration of adult characters into embryogenesis.

Timing of organogenesis underscores the evolution of neonatal life histories and powered flight in bats

“…Nonetheless, the early developmental stage before the serration of the digital plate is a stage in which the species-specific pattern becomes discernible, thereby reflecting the preparatory period that initiates the forelimb elongation in bats. It is pointed out that selection for adult traits often results in significant changes in early organogenesis [6,86,89], referred to as ‘developmental penetrance’ [86]. In talpid moles, for example, Sox9 expression is temporally advanced in the forelimb compared with the hindlimb, resulting in the relative enlargement of the forelimb.…”

“…Mammals exhibit remarkable structural and functional diversity of the limb, contributing to their infiltration into diverse ecological 'niches' and transition to various life histories. Even among closely related taxa, limb function varies depending on movement types [1,2], foraging behaviour [3], and whether the species is precocious or altricial [4][5][6]. Neonates of marsupials, representative of precocious mammals, clamber up the maternal body after birth with their well-developed forelimb, as opposed to their immature hindlimb [7,8].…”

The evolutionary and developmental morphology of domestication in birds and mammals

“…In this special issue, two of the studies are quantitative surveys of the comparative organogenesis of birds (Cordero & Werneburg, 2022) and ungulate mammals (Schlindwein & Werneburg, 2022). Other articles in it illustrate how morphological diversity associated with the domestication process integrates with zooarchaeological research.…”