Mechanisms of Population Change
Adaptations help an organism survive and reproduce in a particular environment
Structural adaptations
Genetic changes in the physical structure or habit of an organism that allow it to survive and reproduce. Include camouflage, sharp talons or claws, and good eye sight
Behavioural Adaptations
The things organisms do to survive; species changes its pattern of action to better suit the environment. Include migrating, nocturnal/diurnal, mating dances and avoidance
Physiological/Biochemical and Body Processes
A systemic response to changes in the environment/processes occurring in the internal part of an animal. Include bioluminescence, producing venoms or poisons and hibernation
How do adaptations develop?
A gradual change in the members of a population over time
Variation
A visible or invisible difference within a species. Not all become adaptations. Can be advantageous, disadvantageous, or have no effect.
Genetics
Each parent has a different set of genes. They pass on these genes which results in different combinations. These combinations make up the variety we see
Mutations
Changes in the genetic material of an organism. Occur spontaneously, when DNA is copied, by UV radiation or by environmental agents. They can be passed on to offspring
Sickle Cell Mutation
Red blood cells are sickle or present shaped and cause clots or reduced blood flow
Beneficial Mutations
Common when an environment is changing. Provides a selective advantage to the organism.
Natural Selection
Results when the characteristics of the population changes because of the individuals that survive and reproduce
Selective pressure
Exerted by the environment that can cause certain individuals to survive, whereas others will not survive. Those that survive and reproduce will pass on their inheritable traits to their offspring
Theory of Evolution
Well known and widely supported theory to explain how species have changed over earths history. Developed by Charles Darwin and published in his book. Changes in populations of organisms occurs over many generations due to natural selection.
Requirements for Evolution
Variation, environment, competition, heritability, and time
Requirements for Evolution: Variation
Differences between individuals
Requirements for Evolution: Environment
Selective pressure for certain traits
Requirements for Evolution: Competition
Infraspecific competition for resources
Requirements for Evolution:Heritability
Traits are passed on to the next generation (inheritance)
Requirements for Evolution: Time
Happens to populations over many generations
Evidence for Evolution: Fossils
Give strong evidence of organisms changing. Have record of many species that lived in the past, obtained by fossil records
What evidence do fossils provide?
Those found in young/higher rock laters are similar to species alive today. They appear in chronological order in the rock layers, and not all appear in the record at the same time
Evidence for Evolution: Transitional Fossils
Fossils that show intermediary lines between groups of organisms. Helped scientists better understand the process of/relationships between organisms.
Biogeography
The study of the past and present geographical distribution go organisms. Continents sed to be together, any organisms found only on one specific continent suggest that they evolved after the breakup
Homologous features
Structures that have similar structural elements and origin but may have a different function. Same origin, different function
Analogous Features
Structures that perform similar functions even though the organisms do not have a common evolutionary origin. different origin, same function
Vestigial Structures
Structures or attributes that have apparently lost most or all of its ancestral function in a given species. Remnant structures with no function
Embryology
Embryos of different organisms have similar stages of development
Molecular Biology
All cells consist of similar structures and components. Enzymes control reactions, and proteins are made form animo acids. All cells that can replicate or duplicate do contain DNA
Lamarck
Presented the first theory of evolution
Lamarck's Theory
While comparing species of animals, he discovered what he thought was a line os descent (a series of fossils that led to a modern species). Believed that new, simple species were continually created by spontaneous generation and evolved to become more com
Spontaneous generation
Living organisms come from non living matter
Lamar's Beliefs
Use and disuse, theory of acquired characteristics, increasing complexity in organisms after spontaneous generation, no extinction
Darwin's Beliefs
Variation, inheritance of characters, differential survival, extinction
Speciation
Formation of a new species. There are two ways a species can form
Transformation
New species gradually develops as a result of mutation and adaptation. The old species is gradually replaced
Divergence
One or more species arise from a parent species that continues to exist.
What must not occur for speciation to happen?
Two populations must not interbreed- they are isolated from one another
Geographical Barriers
Keep populations physically separated. Examples include floods, forest fires, Pangea, natural disaster
Biological Barriers
Exist in the same region but are reproductively isolated
Adaptive Radiation
Diversification of a common ancestral species into a variety of species. Ex. Darwin's finches
Gradualism
A change occurs slowly and steadily in a linear fashion. Large changes result from many small changes
Punctuated Equilibrium
Evolutionary history consists of long periods of little change, interrupted by periods of speciation. Species will change the most when they first diverge form the parent species and then will change very little.