CP Biology Ms. Morrison

 Change over time, process by which modern organisms have descended from ancient organisms

 Well-supported testable explanation of phenomena that have occurred in the natural world

 Traveled around world on HMS Beagle (1831)  Made numerous observations and collected evidence that lead to theory of evolution  Saw great diversity in plant and animal life  Collected fossils on his trip  Questioned fossils relationships to living organisms and wondered why they had disappeared

 Influenced Darwin the most  Group of small islands off west coast of South America  Although close – had very different climates  Observed that the characteristics of many animals and plants varied noticeably among the different islands

 Until 19 th century – thought world was only a few thousand years old and life was like it had always been  Studies of fossils lead to idea that several periods of creation  Two geologists – James Hutton and Charles Lyell – recognized Earth was many million years old and processes that changed Earth in the past were still working now

 Published theory about geological forces that shaped Earth  Said layers of rock form very slowly – pushed up or buried, shaped by natural forces such as rain, heat, and cold  Proposed Earth to be much more than a few thousand years old

 Principles of Geology  Scientists must explain past events in terms of processes that they actually observe since those processes that shaped Earth in past continue in present  Explained geological features could be built up or torn down over long periods of time

 Hutton and Lyell influenced Darwin two ways:  If Earth could change, might life also change?  Would have taken many, many years for life to change – Earth would have to be extremely old

 Jean-Baptiste Lamarck – recognized living things changed over time and all species descended from other species  Realized that organisms somehow adapted to their environments  Published theory in 1809  Proposed that selective use or disuse of organs – caused organisms to acquire or lose certain traits over their lifetimes – these could be passed to offspring and over time lead to change in the species  Incorrect – acquired behaviors NOT passed to offspring

 Thomas Malthus – economist who observed in 1798 that babies were being born faster then people were dying  Reasoned that if human population grows unchecked, that sooner or later there would be insufficient living space and food for everyone  War, famine, and disease – work against population growth  Concept lead Darwin to realize this was true for plants and animals too  Darwin wondered what factors determine which organisms survive and reproduce and which do not

 Published in 1859  Proposed mechanism for evolution was natural selection and proposed evidence for evolution  Said natural variation found in all types of organisms  Humans used selective breeding for particular natural variations found useful = artificial selection  Darwin felt a process like artificial selection occurred in nature

 Struggle for existence = each member of a species completed to obtain food, living space, and other necessities of life  Fitness = ability of an individual to survive and reproduce in its environment  Said fitness result of adaptations (inherited characteristics) that increase an organisms’ chance of survival  Successful adaptations – enable organisms to become better suited to environment and better able to survive and reproduce

 Survival of the fittest = individuals better suited to the environment (high fitness) would survive and reproduce most successfully = natural selection  Over time natural selection results in changes in inherited characteristics of a population which increases a species’ fitness in its environment

 Living species descended with changes from other species over long periods due to natural selection  Means all living organisms related to one another  Principle = common descent = all species, living and extinct, are derived from common ancestors

 Fossil Record – shows living things evolving for millions of years  Geographic distribution of living species  Some species become different when adapt to different local environments  Different species living in similar environments may evolve common features

 Homologous body structures = structures which have different mature forms but develop from same embryonic tissues  Ex. 4 limbed animals with backbones have common ancestor  Some homologous structures do not serve important functions – vestigial organs – have become very reduced in size and not used in survival  Embryonic similarities – embryos of many animals with backbones look so similar it is hard to tell them apart  Same groups of embryonic cells develop in same order and in same patterns  Help produce homologous structures