Exam 2 review summary (chapter 10) PDF

Preview

Summary

chapter 10 summary and take home message...

Description

Chapter 10

The Origin and Div Diversification ersification of LLife ife o on n Earth Chapter Outline 1

Life on ea earth rth most lik likely ely originated fro from m non-living materials. 10.1 Complex organic molecules arise in non-living environments. TAKE-HOME MESSAGE 10.1: Under conditions similar to those on early earth, small organic molecules form, and these molecules have some chemical properties of life.

2 Species are the basic units of biodiv biodiversity ersity ersity.. 10.4 What is a species? TAKE-HOME MESSAGE 10.4: Species are generally defined as populations of individuals that interbreed with each other, or could possibly interbreed, and that cannot interbreed with organisms other such groups. This concept can be applied easily to most plants and animals, but is not applicable for many other types of organisms. 10.6 Species are not always easily defined. TAKE-HOME MESSAGE 10.6: The biological species concept is useful when describing most plants and animals, but it falls short of representing a universal and definitive way of distinguishing many life forms. Difficulties arise when trying to classify asexual species, fossil species, species arising over long periods of time, ring species, and hybridizing species. In these cases, alternative approaches to defining species can be used. 10.7 How do new species arise? TAKE-HOME MESSAGE 10.7: Speciation is the process by which one species splits into two distinct species that are reproductively isolated. It can occur by polyploidy or by a combination of reproductive isolation and genetic divergence.

3 Evolutiona Evolutionary ry trees help us conceptua conceptualize lize and categorize biodiv biodiversity ersity ersity.. 10.8 The history of life can be imagined as a tree. TAKE-HOME MESSAGE 10.8: The history of life can be visualized as a tree; by tracing from the branches back toward the trunk, we can follow the pathway back from descendants to their ancestors. The tree reveals the evolutionary history of all species and the sequence of speciation events that gave rise to them. 10.9 Evolutionary trees show ancestor-descendant relationships. TAKE-HOME MESSAGE 10.9: Evolutionary trees constructed by biologists are hypotheses about the ancestor-descendant relationships among species. The trees represent an attempt to describe which groups are most closely related to which other groups. 10.10 Similar structures don’t always reveal common ancestry.

TAKE-HOME MESSAGE 10.10: Evolutionary trees are best constructed by comparing organisms’ DNA sequences rather than comparing physical similarities, because convergent evolution can cause distantly related organisms to appear closely related, but it doesn’t increase their DNA sequence similarity.

4 Macroev Macroevolution olution gives rise to great di diversity versity versity.. 10.11 Macroevolution is evolution above the species level. TAKE-HOME MESSAGE 10.11: The process of evolution—changes in allele frequencies within a population—in conjunction with reproductive isolation is sufficient to produce speciation and the rich diversity of life on earth. 10.12 The pace of evolution is not constant. TAKE-HOME MESSAGE 10.12: The pace at which evolution occurs can be rapid or very slow. In some cases, the fossil record reveals long periods with little evolutionary change punctuated by rapid periods of change. In other cases, species may change at a more gradual but consistent pace. 10.13 Adaptive radiations are times of extreme diversification. TAKE-HOME MESSAGE 10.13: Adaptive radiations—brief periods of time during which a small number of species diversify into a much larger number of species—tend to be triggered by mass extinctions of potentially competing species, colonizations of new habitats, or the appearance of evolutionary innovations.

10.14 There have been several mass extinctions on earth. TAKE-HOME MESSAGE 10.14: As new species are being created, others are lost through extinction, which may be a consequence of natural selection or large, sudden changes in the environment. Mass extinctions are periods during which a large number of species on earth become extinct over a short period of time.

5

An overvi overview ew of the diversity of lif life e on earth: organisms are divid divided ed into three domains. 10.15 All living organisms are classified into one of three groups. TAKE-HOME MESSAGE 10.15: All life on earth can be divided into three domains—bacteria, archaea, and eukarya—which reflect species’ evolutionary relatedness to each other. Plants and animals are just two of the four kingdoms in the eukarya domain, encompassing only a small fraction of the domain’s diversity. 10.16 The bacteria domain has tremendous biological diversity. TAKE-HOME MESSAGE 10.16: All bacteria share a common ancestor and have a few features in common. They are prokaryotic, asexual, single-celled organisms with no nucleus or organelles, with one or more circular molecules of DNA as their genetic material, and using several methods of exchanging genetic information. Bacteria have a much broader diversity of metabolic and reproductive abilities than do the eukarya. 10.17 The archaea domain includes many species living in extreme environments. TAKE-HOME MESSAGE 10.17: Archaea, many of which are adapted to life in extreme environments, physically resemble bacteria but are more closely related to eukarya. Because they

thrive in many habitats that humans have not yet studied well, including the deepest seas and oceans, they may turn out to be much more common than currently believed. 10.18 The eukarya domain consists of four kingdoms: animals, plants, fungi, and protists. TAKE-HOME MESSAGE 10.18: All living organisms that we can see with the naked eye (and many that are too small to be seen) are eukarya, including all plants, animals, and fungi. The eukarya are unique among the three domains in having cells with organelles....