Abstract
Mammals constitute a rich subject of study on evolution and development and provide model organisms for experimental investigations. They can serve to illustrate how ontogeny and phylogeny can be studied together and how the reconstruction of ancestors of our own evolutionary lineage can be approached. Likewise, mammals can be used to promote 'tree thinking' and can provide an organismal appreciation of evolutionary changes. This subject is suitable for the classroom and to the public at large given the interest and familiarity of people with mammals and their closest relatives. We present a simple exercise in which embryonic development is presented as a transformative process that can be observed, compared, and analyzed. In addition, we provide and discuss a freely available animation on organogenesis and life history evolution in mammals. An evolutionary tree can be the best tool to order and understand those transformations for different species. A simple exercise introduces the subject of changes in developmental timing or heterochrony and its importance in evolution. The developmental perspective is relevant in teaching and outreach efforts for the understanding of evolutionary theory today.
Highlights
Mammals are a diverse group in which to examine development and evolution, and besides the mouse and the rat used in biomedical research, provide subjects based on which experimental (Harjunmaa et al 2014; Montandon et al 2014; Parsons et al 2015) and comparative (Cooper et al 2014) studies have provided major insights
It is implementable without assistance in a class with as many students as the number of developmental series depictions provided (Table 1; Additional files 1–18) or in multiples of that number should pairs or groups of 3 or more students deal with each species
Instead of presenting sets of developmental series uniform in terms of the number of specimens and the time window portrayed, we suggest to provide the students with the plates from the original references (Table 1; Additional files 1–18), as this has the advantage of facing the student with a situation more similar to that encountered in actual comparative embryological work
Summary
Mammals are a diverse group in which to examine development and evolution, and besides the mouse and the rat used in biomedical research, provide subjects based on which experimental (Harjunmaa et al 2014; Montandon et al 2014; Parsons et al 2015) and comparative (Cooper et al 2014) studies have provided major insights. An exercise on comparative organogenesis in vertebrates The activity is designed for use in lecture-type courses but is scalable to large courses and can be performed including discussions in 45 min It is implementable without assistance in a class with as many students as the number of developmental series depictions provided (Table 1; Additional files 1–18) or in multiples of that number should pairs or groups of 3 or more students deal with each species. An example of general similarity between evolutionary and developmental transformation (Macrini 2002; Martin and Ruf 2009; Asher 2012; Ramírez-Chaves et al 2016; Werneburg and Spiekman in press), is the fact that the hand in some stages of mammalian foetuses, including human ones, looks like a paddle (e.g., Fig. 1k) and resembles superficially that of our aquatic ancestors This commonality among species in the transformation series contrasts with the differences in the static stage represented by the adult. Those species are necessary to root the placental tree and to reconstruct the ancestral sequence of character development
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