Chapter 3 Evolution, Systematics and Phylogeny. Ma.Luisa V. Cuaresma Biological Sciences Department. Organic evolution. A change in the genetics of a population over time (generations). Population -all individuals of the same species living in a defined area at the same time.
Ma.Luisa V. Cuaresma
Biological Sciences Department
Fitness – refers to degree to which individuals with certain traits are expected, on average, to survive & reproduce.
Natural selection is simply the logical result of four features of living systems:
1. variation- individuals in a population vary from one another
2. inheritance- parents pass on their traits to their offspring genetically
3.selection - some variants reproduce more than others
4.time - successful variations accumulate over many generations
There are four properties of the population, called Darwin’s Four Postulates that together result in Natural selection…………….
Figure 1. The hierarchical relations between Macroevolution (Ma) and Microevolution (Mi), and the Environment (E). Mi consists of Organisms (O) and their Interactions (I) together with factors from the Environment. Examples A-G illustrate the levels of environmental influence:
A. Mutation caused by chemical, thermal or radioactive interference.
B.Heat shock on developing zygotes.
C.Local adaptation to a niche.
D. Climatological change causing migration.
E. Geographical isolation.
F. Environmental changes that cannot be adapted to for historical or developmental reasons (causing extinction).
G. Changes that affect speciation rates and type.
1. Fossils – provide a preserved record of the history of life forms; portrays the phylogeny of life.
2.Hierarchical pattern of homology – different species that share the same structures depicts that they may have evolved from the same ancestor. (common features / traits shared close relationship of species; less traits shared distant relationships)
Every line that branches into species above the branch (descendants) arised from species below the branch point (ancestor).
Ex: Trees on the right shows the relationship between mouse, bird, lizard, snake.
Trees on the left shows relationship between salamander and frogs.
LIZARDPrimitive and Derived Traits
AAnalyze the figure below and answer the following questions.