This chapter presents the reconstruction of the evolutionary history of lineages. It provides an overview of the basic principles of phylogenetic systematics and the role of fossils in biogeography. Phylogeography refers to an approach that studies the geographic distributions of genealogical lineages within species and among closely related species. The chapter then details the extent of systematics, molecular systematics, fossil record, and molecular clocks estimating times of divergence. It highlights the growing potential of reconstructing biogeographic histories following the progress of available robust lineage histories.
Chapter
Reconstructing the Evolutionary History of Lineages
Chapter
Origin and Radiation of Chondrichthyans
This chapter looks at chondrichthyans, which are not primitive fishes, but are highly developed. The first definitive chondrichthyan fossils came from the Early Devonian period, although chondrichthyan-like scales are known to have existed from the early Silurian, and possibly the Ordovician periods. The chapter highlights the two main branches of chondrichthyans which reflect a division which had occurred by the start of the Devonian. Elasmobranchii includes the extant neoselachians and extinct relatives, while Holocephali includes the extant chimaeras and related extinct forms. The chapter shows that chimaeras have a single gill opening covered by soft tissue and an immobile upper jaw fused with the skull. It then considers the ecological implications of declining populations of the elasmobranch species, referring to how the life-history characteristics of neoselachians make them vulnerable to overfishing. Policies to protect these specieis revolve around sustainable exploitation of individual species.
Chapter
Origins of Lissamphibia and Amniota
This chapter examines the origins of lissamphibia and amniota. It provides an overview of Paleozoic tetrapods, which includes the taxa on the divergence and diversification of lissamphibians and amniotes. Evolutionary changes in skulls, vertebrae, limb girdles, limbs, and ankles have enabled the tracking of the diversification of Paleozoic tetrapods and the interpretation of aspects of their biology. Meanwhile, the evolution of the amniotic egg in the Carboniferous has allowed amniotes to escape their dependence on water for reproduction. The chapter details the characteristics of amniotes that allowed for greater independence from moist habitats and the ability to grow very large. It explains how studying fossils can result in a greater understanding of the biology, ecology, and functional morphology of amniotes and their subsequent diversification.
Chapter
The History of Life
This chapter explores the history of life by studying fossils. Fossils provide direct
evidence of events of extinction, diversification, and the movement of continents and
climate that affected species. Moreover, evidence from living organisms indicates that all
living things are descended from a single common ancestor. The chapter then details the
history of the Cenozoic era, Mesozoic era, Paleozic era, and Precambrian era. It explains
how the most devastating mass extinction at the end of the Permian resulted in the massive
alteration of the taxonomic composition of the Earth's biota. Human population growth
and technology also had an accelerating impact on biological diversity and major
extinction.
Chapter
Human Evolution
This chapter assesses the role of genomics in studying human evolution. Genome sequences tell us how we differ genetically from other apes, fossils fill in details of some of the extinct species, and ancient DNA (aDNA) can even allow us to read their genome sequences. The Homo sapiens originated in Africa, around 300,000 years ago, and then expanded into most of Asia, Australia, and Europe, as well as the Americas. During these expansions, they mixed with other forms of early human, Neanderthals and Denisovans, so that all non-Africans carry about 2 per cent of Neanderthal DNA, which influences our characteristics such as hair and skin colour, virus resistance, and diabetes risk. Striking examples of local genetic adaptation whose genetic basis is understood are the lighter skin colour seen in Asia and Europe, and the ability of adults in some places, but not others, to digest fresh milk.
Chapter
What’s the Evidence?
This chapter examines the evidence for evolution that we can see through looking at fossils, anatomy, biochemistry, ecological genetics, and genomics. Fossils are the most familiar evidence for evolution since they gave proof of life in the past geological ages. Anatomy studies the structure of living organisms and its comparison to other groups of organisms gives clues to evolutionary relationships. The science of biochemistry depends on the development of tools and techniques that spark new insights into the natural world. Genomics, on the other hand, showcases the formation of species such as DNA. The chapter also gives an overview of developmental biology which capitalizes on the emergence of genomics.
Chapter
Human Evolution: Where Do We Come From and How Did We Get Here?
This chapter examines the theory of human evolution. The forces of evolution (such as gene flow and natural selection) serve as a mould for the human species through time, thus research on human evolution is constrained by ancestral animals. The chapter examines animals such as primates and argues that they are the possible evolution ancestor of humans. The chapter also looks at human characteristics such as bipedalism, facial morphology, dentition, and brain expansion. It notes that Hominini, whose fossils were found in Africa, are the earliest members of the human family on record. DNA has helped determine the genetic relationships and similarities among modern animals.
Chapter
The Human Story So Far: the Fossil Record
This chapter looks into the fossil record of the ancestor of humans. It examines the evidence for the genus Homo across the world. It argues that Homo erectus was the first hominin to engage in hunting in Africa. The chapter shows that studying the development of early technologies provides clues to humans' evolutionary journey. Examples of recovered human fossils include the discovery of evidence of Neanderthals in a cave site in the Neander Valley in France in 1856. According to DNA, interbreeding took place between Neanderthals and modern humans. Moreover, DNA, X-rays, computer statistical analyses, and dating techniques have furthered the studies into the origins of humans and the theory of human evolution.
Chapter
What is macroevolution? What is macroecology?
This chapter starts by defining macroevolution and macroecology. Macroevolution focuses on changing patterns of biological diversity across time, space, and lineages. Meanwhile, macroecology concerns broad-scale patterns in the abundance and distribution of species. Evolution and ecology are central to the study of biology, and the key to understanding the world around us. Not surprisingly, evolution and ecology are taking an increasingly prominent role in biological education. The chapter then provides a brief, selective account that highlights some key ideas relevant to contemporary research in macroevolution and macroecology. These include Jean-Baptiste Lamarck's evolutionary theory; the role of fossils in revealing the history of the living world; uniformitarianism; evolution by natural selection; and Darwinism. The chapter also considers the challenge of testing hypotheses in macroevolution. Testing claims about the natural world lies at the heart of a scientific investigation, but there are many possible ways to conduct a scientific test.
Chapter
Were dinosaurs evolutionary failures?
This chapter focuses on dinosaurs as a case study for examining the macroevolutionary processes of adaptive radiation and mass extinction. Considering the rise of dinosaurs allows us to examine the role of both key adaptations and chance in diversification, while considering their fall prompts us to examine our ability to resolve events and determine cause and effect in deep time. The study of fossils sheds light on physiology, locomotion, behaviour, and ecology of extinct species. The diversification of dinosaurs may have been driven by key adaptations, such as upright gait and fast metabolism, which allowed them to exploit a wide range of niches, or it may have been triggered by opportunity through the extinction of other reptile groups. Given that vertebrate fossils are rare, and biased in terms of location, taxa, and time period, there is some uncertainty over the timing and nature of dinosaur extinctions.
Chapter
The Ancestry of Life
This chapter details the evolutionary history of the modern groups discussed in the previous chapter and describes their ancient ancestors. The age of a group of organisms can be estimated from the age of the rocks in which the earliest fossils belonging to this group have been found. However, this is only the minimum age of the group because still earlier representatives may not have fossilized or their fossils may not have been found yet. If the rate of neutral mutation were constant over genes and lineages, DNA sequences could also be used to estimate absolute ages, independently of fossils. Ultimately, any given clade descends (to the exclusion of all other clades) from a most recent common ancestor that lived at some time in the past. The chapter considers the ancestry of Homo sapiens, Hominoidea, Primates, Eutheria, Mammalia, Amniota, Tetrapoda, Sarcopterygii, Osteichthyes (bony fishes), Gnathostomata, Chordata, Deuterostomia, Bilateria, Metazoa, Unikonta, and Eukaryota.
