Origins of Biological Diversity Chapter 15 Origins of Biological Diversity

15.1 Diversity of Life biological species concept: defines a species as a population or group of populations whose members have the ability to breed with one another in nature and produce fertile offspring. asexual reproducers not included fossils also not included

Macroevolution macroevolution: dramatic biological changes origin of different species extinction of species evolution of major features speciation: origin of a new species Biological diversity

Reproductive Barriers reproductive isolation: reproductive barrier keeps two species from breeding Timing different breeding seasons Behavior different courtship or mating behaviors Habitat adapted to different habitats in the same area Others reproductive structures incompatible zygote fails to develop hybrid cannot reproduce (ex. mules, wolf hybrids)

Geographic Isolation geographic isolation: separation of populations as a result of geographic change or dispersal to geographically isolated places separation of “splinter” populations is crucial to evolution; genetic drift

Adaptive Radiation adaptive radiation: evolution from a common ancestor that results in diverse species adapted to different environments Hawaiian islands; different species on each island

Punctuated Equilibrium punctuated equilibrium: species often diverge in spurts of relatively rapid change Long periods of little change in a species are broken by shorter times of speciation Successful species last 1-5 million years; unique changes in first 50,000 years

15.2 Remodeling Process Refinement of Existing Adaptations Complex structure may have evolved from a simpler structure having the same basic function Example: eye refinement – light-sensitive cells

Adaptation of Existing Structures to New Functions chitin – forms the exoskeleton of arthropods; protection in ocean land-dwelling – resists water loss Penguins have modified wings for swimming

Evolution and Development embryology: study of the processes of multicellular organisms as they develop from fertilized eggs to fully formed organisms mutation in master control gene has bizarre effects; cow with head-leg less dramatic; subtle changes in development feet of salamanders slightly different based on habitat; trees vs. land

15.3 Fossil Record geologic time scale: organizes Earth's history into four distinct ages known as the Precambrian, Paleozoic, Mesozoic, and Cenozoic eras Era  Period  Epoch

Dating Fossils relative age: reflect the order in which groups of species existed compared to one another absolute age: actual age in years radiometric dating: based on the measurement of certain radioactive isotopes in objects isotopes have fixed rate of decay half-life: the number of years it takes for 50 percent of the original sample to decay Uranium-238 : half-life of 4.5 billion years, has been used to date rocks of the Precambrian era and the Cambrian period not present in living organisms Carbon-12 and carbon-14: calculate how long the organism’s been dead half-life of 5,730 years; only recent fossils

Continental Drift Continental Drift: motion of continents about Earth's surface on plates of crust floating on the hot mantle North America and Europe drifting apart at 2 cm per year Explains how fossils are similar on different continents Pangaea- supercontinent about 245 million years ago climate change and competition; extinction of species

Mass Extinctions Mass extinctions: brief episodes of great species loss Cretaceous period, 65 million years ago, extinction of dinosaurs 1. Climate cooling and shallow seas receding 2. Meteor in the Yucatan; polluted the sky with dust, blocking sun 3. Rise of mammals Permian period; 90% of marine animal species Provide new opportunities for other species and new evolution

15.4 Taxonomy taxonomy: branch of biology that involves the identification, naming, and classification of species.

Linnaean System of Classification Carolus Linnaeus (1707 – 1778) 1. binomial: two-part Latin name for each species first part is genus ; first letter capitalized second part is species; all lower case ex. Homo sapien 2. hierarchy – broader to specific species Kingdom Phylum Class Order Family Genus Species

phylogenetic tree: a diagram that reflects hypotheses of evolutionary relationships with a branching pattern greater the number of homologous structures, more closely related

Convergent Evolution convergent evolution: process in which unrelated species from similar environments have adaptations that seem very similar analogous structures: similar adaptations that result from convergent evolution ex. wings of insects and birds; no common ancestor DNA comparisons between species increase evidence of relationships

Cladistics cladistics: method of determining the sequence of branching clade: each evolutionary branch in a phylogenic tree consists of ancestral species and all descendants derived characters: all organisms in clade share homologous structures that do not occur outside the clade cladogram: a phylogenetic diagram that specifies the derived characters of clades not always accurate because birds and reptiles are similar

Classification Systems Old = 5 Kingdoms Monera Protista Fungi Plantae Animalia New = 3 Domains Bacteria Archaea Eukarya