The study of biological diversity and evolutionary relationships among organisms is

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What is the study of evolutionary relationships between organisms called?
What is the study of phylogeny?
Is the study of biological diversity in an evolutionary context?
What is evolutionary relationship in biology?

Theme course requirements can be found in the Evolution and Biodiversity Theme Charts calendar entry.

Biodiversity refers to the variety of life on Earth. It includes species diversity (i.e., the variety of different types of organisms), genetic diversity within each species, and ecosytem diversity. The Evolution and Biodiversity theme deals primarily with the evolutionary processes that generate and maintain (or limit) organismal and genetic diversity, patterns of species biodiversity in time and space, and the biology and evolutionary relationships within the specific organismal groups.

Evolution and Biodiversity theme members conduct research on various aspects of biodiversity from both evolutionary and conservation-related perspectives. Current research on adaptation includes the evolution of flower shape in response to animal pollinators, the genetic basis of adaptation, and the evolution and maintenance of sociality and mating systems. Research on species and genetic diversity includes the systematics and conservation biology of a wide range of organisms (e.g., lichens, vascular plants, fish and other vertebrates) and the study of biological diversity as it relates to human well-being and sustainability.

Major Summary Sheet (including Co-op)

Honours Summary Sheet (including Co-op)

Phylogenetics is the study of evolutionary relationships among biological entities – often species, individuals or genes (which may be referred to as taxa). The major elements of phylogenetics are summarised in Figure 1 below.

Figure 1 Elements of phylogenetics.

Typically phylogeneticists study one of the following types of question:

What are the evolutionary relationships or histories among my species/individuals/genes of interest?
How do sequences evolve?
Can I better describe processes of sequence evolution with a mathematical model?

We can reconstruct a phylogenetic tree by looking at the nucleotide or protein sequences and combining this with our understanding of sequence evolution, which is described using an evolutionary model. This enables us to infer evolutionary events that happened in the past, and also provides more information about the evolutionary processes operating on sequences. Thus we may refine our understanding of how evolution works and develop better mathematical models of evolution.

Overview

The famous paleontologist George Gaylord Simpson defined systematics as the "scientific study of the kinds and diversity of organisms and of any and all relationships among them" (1961, p. 7). In more general terms, systematics can be thought of as the study of biodiversity.

This field of systematics has two major components: taxonomy and phylogenetics.

Taxonomy is the field of biology and paleontology that concerns the naming of living (extant) and ancient (extinct) plants, animals, and other organisms. This process is governed by a universal system of rules and conventions derived from the approach pioneered by Carl Linnaeus in the 18th century. The subject of taxonomy--which underpins our ability to communicate about biological diversity--is explored in Section 1 of this chapter.

Phylogenetics is the study of the evolutionary relationships among organisms. These relationships are typically depicted by tree-like diagrams. Section 2 of this chapter focuses on several topics related to phylogenetics, including an overview of how to read phylogenetic trees (Section 2.1), how to build phylogenetic trees (Section 2.2), and how to understand the evolution of the characteristics of organisms using phylogenetic trees (Section 2.3).

Systematics is the study of biodiversity. Systematists name and describe organisms (taxonomy) and determine their relationships (phylogenetics). Image shows a Monarch butterfly (Danaus plexippus Linnaeus, 1758), as well as an early description of the species by Lamarck (1835) (top inset) and a modern phylogenetic hypothesis (lower inset) for the species (image modified from fig. 4a in Shi et al., 2015 in PLoS ONE; image license: Creative Commons Attribution 4.0 International (CC BY 4.0)).

The connection--and sometimes source of conflict--between taxonomy and phylogenetics is classification. Scientific classification schemes that organize and convey information about biological diversity predate the discovery of evolution. Naturalists long ago found it useful to have a convenient way to communicate about the diversity of life on Earth, at both narrow scales (such as individual species) and broader scales (major groups like flowering plants, snails, or chipmunks). Classifications were initially developed to reflect the apparent order that is observed in nature, which was presumed to be the result of the Divine Plan of a Creator. Later, it was determined that this order is a result of biological evolution, and that hierarchical groupings of organisms possess similar features because of shared common ancestry.

Paradoxically, information about phylogenetic relationships can sometimes complicate seemingly self-evident classification schemes. For example, we commonly refer to birds and dinosaurs as though they are distinct groups of organisms, although birds descended from one group of dinosaurs called theropods. Because of this, should we instead call birds theropods? Section 2.4 considers the relationships between phylogenetic trees and classifications.

Review

Question

What is systematics?

Answer

Systematics is the study of biodiversity.

Question

What is phylogenetics?

Answer

Phylogenetics is the study of the evolutionary relationships between organisms.

Question

What is the field of biology called that concerns the naming of organisms?

References

Shi, Q.-H., X.-Y. Sun, Y.-L. Wang, J.-S. Hao, Q. Yang. 2015. Morphological characters are compatible with mitogenomic data in resolving the phylogeny of nymphalid butterflies (Lepidoptera: Papilionoidea: Nymphalidae). PLoS ONE 10(4): e0124349. https://doi.org/10.1371/journal.pone.0124349.

Simpson, G. G. 1961. Principles of Animal Taxonomy. Columbia University Press, New York, 247 pp.

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What is the study of evolutionary relationships between organisms called?

Species can also be defined based on a shared evolutionary history and ancestry. This method of defining species is called phylogenetics, which is the study of the evolutionary relationships among organisms.

What is the study of phylogeny?

Tracing the Evolutionary Steps Using Phylogeny Phylogenetics is the science of studying the evolutionary relatedness among biological groups and a phylogenetic tree is used to graphically represent this evolutionary relation related to the species of interest (Figs.