Evolutionary Patterns, Rates, and Trends AP Biology: Chapter 19 Starr & Taggart – 11th Edition

Key Concepts: All species that have ever lived are related Macroevolution refers to patterns, trends, and rates of change among lineages over geologic time Fossil and geologic records and radiometric dating of rocks provide evidence of macroevolution Chapter 19

Key Concepts: Anatomical comparisons help reconstruct patterns of change through time Biochemical comparisons also provide evidence of macroevolution Diversity characterizes the distribution of species through time Taxonomy is concerned with identifying and naming new species Chapter 19

Macroevolution Large scale patterns, trends and rates of change among families and other more inclusive groups of species. Chapter 19

What is a Species? A mixed herd of zebroids & horses. Zebroids – are interspecies hybrids (horses & zebras) Chapter 19

What is a Species? Morphological Species Concept ♂ & ♀ fish Morphological Species Concept Based on appearance alone Biological Species Concept A species is one or more populations of individuals that are interbreeding under natural conditions and producing fertile offspring, and are reproductively isolated from other such populations Two plants of the same species Chapter 19

Species Example Lions and tigers do not meet in the wild, so don’t interbreed; in captivity can mate to produce a liger (sterile) Chapter 19

Reproductive Isolation Cornerstone of the biological species concept Speciation is the attainment of reproductive isolation Reproductive isolation arises as a by-product of genetic change Chapter 19

Reproductive Isolating Mechanisms Any heritable feature of body, form, functioning, or behavior that prevents breeding between one or more genetically divergent populations Prezygotic or Postzygotic Prezygotic- Mechanical isolation Chapter 19

Types of Isolation Chapter 19

Isolating Mechanisms Chapter 19

Pre-Zygotic Isolation Temporal- cicada Pre-Zygotic Isolation Mating or zygote formation is blocked Temporal Isolation Behavioral Isolation Mechanical Isolation Ecological Isolation Gamete Mortality Behavioral - albatross Chapter 19

Post-Zygotic Isolation Takes effect after hybrid zygotes form Zygotic mortality - Egg is fertilized but zygote or embryo dies Hybrid inviability - First generation hybrid forms but shows low fitness Hybrid infertility - Hybrid is fully or partially sterile Chapter 19

Genetic Divergence Gradual accumulation of differences in the gene pools of genetically separated populations Natural selection, genetic drift and mutation can contribute to divergence Gene flow counters genetic divergence Chapter 19

Mechanisms of Speciation Allopatric speciation Sympatric speciation Parapatric speciation Chapter 19

Allopatric Speciation Physical barrier prevents gene flow between populations of a species Effectiveness of barrier varies with species Archipelago hotbed of speciation Chapter 19

Allopatric Speciation on Archipelagos (Island Chain) Chapter 19 Hawaiian Honeycreepers

Hawaiian Honeycreepers Chapter 19

Allopatric Speciation Physical separation between populations promotes genetic changes that eventually lead to speciation. Chapter 19

Speciation without a Barrier Sympatric speciation Species form within the home range of the parent species Parapatric speciation Neighboring populations become distinct species while maintaining contact along a common barrier Chapter 19

Sympatric Speciation New species forms within home range Polyploidy leads to speciation in plants Self-fertilization and asexual reproduction Chapter 19

Sympatric Speciation A species forms within the home range of an existing species, in the absence of a physical barrier. A lake in West Africa in which 9 species of cichlids (a small fish) evolved. Chapter 19

Speciation by Polyploidy Change in chromosome number (3n, 4n, etc.) Offspring with altered chromosome number cannot breed with parent population Common mechanism of speciation in flowering plants Polyploidy cotton Chapter 19

Allopatric vs. Sympatric Speciation Chapter 19

Parapatric Speciation Neighboring populations become distinct species while maintaining contact along a common border, the hybrid zone. Bullock’s oriole Baltimore oriole Chapter 19

Models of Speciation Models of speciation Chapter 19

Patterns of Change in a Lineage Cladogenesis Branching pattern Lineage splits, isolated populations diverge Anagenesis No branching Changes occur within single lineage Gene flow throughout process Chapter 19

Evolutionary Trees extinction (branch ended before present) new species branch point (a time of divergence, speciation) a single lineage a new species extinction (branch ended before present) dashed line (only sketchy evidence of presumed evolutionary relationship) Chapter 19

Gradual Model Speciation model in which species emerge through many small morphological changes that accumulate over a long time period Fits well with evidence from certain lineages in fossil record Time Punctuated equilibrium Gradualism Chapter 19

Punctuation Model Speciation model in which most changes in morphology are compressed into brief period near onset of divergence Supported by fossil evidence in some lineages Chapter 19

Adaptive Radiation Burst of divergence Single lineage gives rise to many new species New species fill vacant adaptive zone Adaptive zone is “way of life” Chapter 19

Extinction Irrevocable loss of a species Mass extinctions have played a major role in evolutionary history Fossil record shows 20 or more large-scale extinctions Reduced diversity is followed by adaptive radiation Chapter 19

Who Survives? Species survival is to some extent random Asteroids have repeatedly struck Earth, destroying many lineages Changes in global temperature favor lineages that are widely distributed Mass extinctions Chapter 19

Identifying Species Past and Present Taxonomy – field of biology concerned with identifying, naming and classifying species Somewhat subjective Devised by Carl von Linne Assigning species names Binomial nomenclature system Genus (generic) and Species (specific) Higher Taxa Family, Order, Class, Phylum, and Kingdom Chapter 19

Phylogeny The scientific study of evolutionary relationships among species Practical applications Allows predictions about the needs or weaknesses of one species on the basis of its known relationship to another Chapter 19

Examples of Classification Chapter 19

How Many Kingdoms? Whittaker’s Five-Kingdom Scheme (1969) Monera Protista Fungi Plantae Animalia Chapter 19

Six Kingdom Scheme Carl Woese Includes the Archaebacteria Eubacteria Protista Fungi Plantae Animalia Chapter 19

Three Domain Scheme Favored by microbiologists Eubacteria Archaebacteria Eukaryotes EUBACTERIA (Bacteria) ARCHAEBACTERIA (Archaea) EUKARYOTES (Eukarya) Chapter 19

Constructing A Cladogram Taxon Traits (Characters) Jaws Limbs Hair Lungs Tail Shell Lamprey - - - - + - Turtle + + - + + + Cat + + + + + - Constructing A Cladogram Gorilla + + + + - - Lungfish + - - + + - Trout + - - - + - Human + + + + - - Taxon Traits (Characters) Jaws Limbs Hair Lungs Tail Shell Lamprey 1 Turtle 1 1 1 1 1 Cat 1 1 1 1 1 Please note: the tail column was changed as it was incorrect in the text. Gorilla 1 1 1 1 Lungfish 1 1 1 Trout 1 1 Chapter 19 Human 1 1 1 1

Constructing a Cladogram lamprey turtle, gorilla, trout, cat, lungfish, human jaws Chapter 19

Constructing a Cladogram turtle, gorilla, cat, lungfish, human lamprey trout lungs jaws Chapter 19

Constructing a Cladogram lamprey trout lungfish turtle, gorilla, cat, human limbs lungs jaws Chapter 19

Constructing a Cladogram lamprey trout lungfish turtle gorilla, cat, human hair limbs lungs jaws Chapter 19

Constructing a Cladogram lamprey trout lungfish turtle cat gorilla human tail loss hair limbs lungs jaws Chapter 19

Constructing a Cladogram Chapter 19

Evolutionary Tree ANIMALS PLANTS arthropods FUNGI chordates flowering plants conifers annelids round-worms ginkgos sac club mollusks echino-derms fungi fungi cycads horsetails rotifers zygospore- ferns forming flatworms fungi lycophytes cnidarians bryophytes chlorophytes sponges chytrids green algae amoeboid PROTISTANS protozoans (stramenopiles) brown algae red ciliates (alveolates) algae chrysophytes sporozoans oomycotes ? dinoflagellates crown of eukaryotes slime molds (rapid divergences) euglenoids kinetoplastids parabasalids (e.g., Trichomonas) EUBACTERIA diplomonads spirochetes ARCHAEBACTERIA (e.g., Giardia) extreme Gram-positive bacteria chlamydias methanogens halophiles cyanobacteria proteobacteria extreme thermophiles Chapter 19 molecular origin of life

In Conclusion Macroevolution is the study of patterns, trends, or rates of change among groups of species over long periods of time There is extensive evidence of evolution based on similarities and differences in body form, function, behavior, and biochemistry Completeness of fossil records are variable Fossil and geologic record show that such changes have influenced evolution Chapter 19

In Conclusion Comparative morphology reveals similarities in embryonic development and identified homologous structures Comparative biochemistry has identified similarities and differences among species Taxonomists identify, name, and classify species Chapter 19