How Biological Diversity Evolves Chapter 14

The origin of species What accounts for all the diversity in the millions of species (extinct and extant) on our planet? What makes these two meadowlarks different? A variety of barriers prevent interbreeding Eastern and western meadowlarks are two different species and do not interbreed

Prezygotic barriers Temporal Isolation Skunk species that mate at different times

Prezygotic barriers Habitat/Ecological Isolation Garter snake species from different habitats

Prezygotic barriers Behavioral Isolation Mating ritual of blue-footed boobies

Prezygotic barriers Mechanical Isolation Snail species whose genital openings cannot align

Prezygotic barriers Gametic Isolation Sea urchin species whose gametes cannot fuse

Postzygotic barriers Reduced Hybrid Viability Frail hybrid salamander offspring

Postzygotic barriers Reduced Hybrid Fertility Horse Donkey Mule Mule (sterile hybrid of horse and donkey)

Postzygotic barriers Hybrid Breakdown Sterile next-generation rice hybrid

INDIVIDUALS OF DIFFERENT SPECIES Prezygotic Barriers Temporal isolation Habitat isolation Behavioral isolation MATING ATTEMPT Mechanical isolation Gametic isolation FERTILIZATION (ZYGOTE FORMS) Postzygotic Barriers Reduced hybrid viability Reduced hybrid fertility Hybrid breakdown VIABLE, FERTILE OFFSPRING No Barriers

Mechanisms for speciation Allopatric speciation Sympatric speciation

Allopatric speciation Ammospermophilus harrisii Ammospermophilus leucurus

Sympatric speciation Chromosomes cannot pair Asexual reproduction Species A 2n  4 Gamete n  2 Sterile hybrid n  5 Can reproduce asexually Viable, fertile hybrid species 2n  10 Gamete n  3 Species B 2n  6

The fossil record in strata

Plate tectonics and biogeography North American Plate Eurasian Plate Philippine Plate ATLANTIC OCEAN Juan de Fuca Plate Caribbean Plate Arabian Plate Indian Plate Cocos Plate South American Plate Pacific Plate Nazca Plate Australian Plate African Plate PACIFIC OCEAN Scotia Plate Antarctic Plate Key Zones of violent tectonic activity Direction of movement

Pangea “all land” Present Cenozoic India collides with Eurasia. 65 135 North America Eurasia 65 Africa South America India Madagascar Australia Antarctica Laurasia 135 Pangaea splits into Laurasia and Gondwana. Gondwana Mesozoic 251 million years ago Pangaea Paleozoic Pangaea is formed.

Biogeography Australia and its neighboring islands are home to more than 200 species of marsupials, most of which are found nowhere else in the world Sugar glider, an omnivore Tasmanian devil, a carnivore Koala, an herbivore

Phylogeny for some of the members of the order Carnivora Figure 14.22 Order Family Genus Species Panthera pardus (leopard) Felidae Panthera Mephitis mephitis (striped skunk) Mephitis Carnivora Mustelidae Lutra lutra (European otter) Lutra Canis latrans (coyote) Phylogeny for some of the members of the order Carnivora Canidae Canis Canis lupus (wolf)

Practical application of phylogenies Growing food Researchers have identified two species of wild grasses that may be maize’s closest living relatives The genomes of these plants may harbor alleles that offer disease resistance or other useful traits that could be transferred into cultivated maize

Analogous structures

Cladistics diagram or cladogram Iguana Outgroup (reptile) Duck-billed platypus Hair, mammary glands Kangaroo Ingroup (mammals) Gestation Beaver Long gestation

Classification: a work in progress Phylogenetic trees are hypotheses about evolutionary history Linnaeus divided all known forms of life between the plant and animal kingdoms This two-kingdom system prevailed in biology for over 200 years In the mid-1900s, the two-kingdom system was replaced by a five-kingdom system that placed all prokaryotes in one kingdom and divided the eukaryotes among four other kingdoms In the late 1900s, molecular studies and cladistics led to the development of a three-domain system, recognizing two domains of prokaryotes (Bacteria and Archaea) and one domain of eukaryotes (Eukarya) The domain Eukarya is currently divided into kingdoms, but the exact number of kingdoms is still under debate