BT101 Midterm Merged PPT Handouts

Lecture 01

Introduction to Ecology:

The word ‘ecology’ was first used by Ernest Haeckel in 1869. Ecology is the scientific study of the interactions that determine the distribution and abundance of organisms in an environment. All organisms have to interact with both living & non living things that surround them. Both these living & non living factors contribute to the whole environment of organisms in which they live.

Ecology is a complex and an amazing field of biology that describes the richness of the biosphere. The basic concept of ecology is that, “all organisms in an environment are interdependent”. So environment is a main part of the relationship that occurs between organism and their natural and manmade environment.

Major components of ecology are Species

Community Ecosystem Biome Biosphere

Sub fields of ecology

 Organismal ecology  Population ecology  Community ecology  Ecosystem ecology  Landscape ecology  Global ecology

Lecture 02

Cell is the basic structural and functional unit of life. All organisms are composed of cells which is the basic concept of cell theory. Organisms may consist of single cell (unicellular) or many cells (multicellular).

Level of organization: Cell

The cell is the simplest collection of matter that can live. Cell structure is correlated to cellular function. 10 µm Organisms are divided into two types on the basis of their cell structure. Prokaryotes Eukaryotes

Prokaryotes consist of only unicellular organisms while Eukaryotes consist of both unicellular and multicellular organisms.

Prokaryotes:

They lack well defined nucleus and also membrane bound organelles.

Eukaryotes

They have well defined nucleus and also have Membrane Bound organelles.

Lecture 03

Species:

A group of sexually reproducing organisms, that can mate and produce fertile offspring. This is the biological concept of species. Every organism is a member of a particular species with specific traits. The species is the largest unit of population in which gene flow is possible. It is defined by reproductive isolation from other species in natural environments.

Four basic concepts about species are

1. Biological species concept 2. Ecological species concept 3. Morphological species concept 4. Phylogenetic species concept

1. Biological concept of species:

Defines species on the base of their interbreeding potential not on similarity or appearance. The Western meadowlark (left) and the Eastern meadowlark (right) appear to be identical, and their ranges overlap, but their distinct songs prevent interbreeding. For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed to each other thus, they are separate species according to this definition.

2. Ecological species concept

Defines species in terms of its ecological niche.

3. Morphological species concept

Defines species by structural features.

4. Phylogenetic · species concept: · Defines species as · the smallest group · of individuals on a · phylogenetic tree. · Lecture 04

A group of same species located at the same place and same time is called as a population. Population biologists study groups in a specific area. A group of ducks would not be a population if there were mallard and wood ducks combined. It means that there are two populations existing in the same area.

Every population has · particular · characteristics:

Population size Population growth Population distribution Population density Organisms are born & the population size increases. Other factors that will increase the size of a population are:  Reproductive fitness  Good weather  Medicine  Geographic isolation  No predators