Ch 25 - The history of life on earth (1 slide per page)-2

Determined by hox genes tetrapod limb development

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: location of limb, bone, flower petal etc. • Determined by Hox genes Tetrapod limb development •Fish fins do not have support •Slight change gives support 71 Developmental gene modifications 1. Changes in timing 2. Changes in spatial pattern 3. New genes and changes in genes 72 Developmental gene modifications 1. Changes in timing 2. Changes in spatial pattern 3. New genes and changes in genes • Invertebrates have single Hox cluster • Hox duplicated ~520 mya in lineage that produced vertebrates • duplicated again ~425 mya • duplicate genes took on new roles • development of backbone, jaws etc. Refer to Figure 25.23 & 25.24 (Campbell 9th ed) 73 Processes determining the rise and fall of groups of organisms 1. Adaptive Radiation 2. Continental Drift 3. Mass Extinction 74 Continental Drift Helps explain current species distribution patterns • Reverse previous changes: species become isolated & start adapting to local environments Continental drift continues! Further breakup of large land masses Pangaea splits into Laurasia and Gondwana • Previously isolated species come into contact • Shallow seas eliminated: many marine species go extinct • Change in local climates: vast inland deserts form Pangaea: all land joined into one supercontinent 75 Biogeography The study of the geographic distributions of species and the historical explanation of these patterns. Why are living or fossilized lungfish found on all continents? Evolved when Pangaea existed 76 Biogeography Ratites - Flightless birds - breastbone w/o keel - Why are All known living & extinct species endemic to the southern hemisphere? Cassowary American rhea Ostrich Elephant bird Emu Moa Kiwi 77 Biogeography Evolved on Gondwana Cassowary American rhea Ostrich Elephant bird Emu Moa Kiwi 79 Processes determin...
View Full Document

Ask a homework question - tutors are online