The nature of evolutionary forces
rubabThe forces which bring about evolutionary changes by natural selection are called evolutionary forces. These forces are random genetic drift, gene flow and mutation. 1. Genetic drift The change in…
RATES OF EVOLUTION
abidaThere are two models of evolution based on the rate of evolution. The concept that evolutionary changes occurs gradually over millions of years is called phyletic gradualism. Charles Darwin believes…
REPRODUCTIVE STRATEGY
sanaThe basis of reproductive strategies is the survival of plant in particular habitat. These reproductive strategies are developed by natural selection. Every organism reproduces to maintain their specie. Each organism…
SPECIES AND SPECIATION
Definition of biological specie: Taxonomists classify organisms according to their similarities and differences. The fundamental unit of classification is the species. Unfortunately, it is difficult to define species. According to…
DEMOGRAPHY
The study of the vital statistics that affect population size is called demography. Birth rate and death rate vary among subgroups within a population. This birth rate and death rate…
SEED BANK
The storage of seed in the soil is called seed bank. Seeds fall on the soil. They are buried in the soil. Some seeds germinate to form the new plants.…
SEED DISPERSAL
Seed is an important source of dispersal of species of a plant to other places. Seeds are dispersed to far off places. Thus the genes of a population of plant…
Phylum Cnidaria (COELENTERATA)
saadiaPHYLUM CNIDARIA (COELENTERATA) (Or. knide, nettle) Members of the phylum Cnidaria possess radial or biradial symmetry. Biradial symmetryis a modification of radial symmetry . In this case, a single plane…
Natural Selection Reexamined
The theory of natural selection remains very important in the modern biology. Some phenotypes are more successful. They leave more offspring than the other phenotypes. It is a natural selection.…
POPULATION
The number of individuals of specie living in the same area at the same time is called population. Population has two aspects: number of individuals of a specie and area…