Download presentation
Presentation is loading. Please wait.
Published byDerick McKinney Modified over 9 years ago
1
CP Biology Ms. Morrison
2
Change over time, process by which modern organisms have descended from ancient organisms
3
Well-supported testable explanation of phenomena that have occurred in the natural world
4
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
5
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
6
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
7
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
8
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
9
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
10
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
11
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
12
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
13
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
14
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
15
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
16
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
17
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
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.