Lecture 1
Introduction
Environment- Environment means surrounding(almost everything including living and non-living being). Everything that has influence on the organism during its lifetime.
Carlyle(English scholar) coined the term environment while he was translating the German word Umgebung. He coined environment from French word Environia(surround)
Ecology- Derived from the Greek word Oiko(Home) + Logy(Study). in 1866 by the German scientist Ernst Haeckel coined the term Ecology.
Study of interaction among different components of the Environment/Ecosystem.
Organism → Organism
Organism → Surrounding (Living → Non-living being)
Ecosystem- The term ecosystem was coined by Arthur Roy Clapha and first time used by his co worker Arthur Tansley(British ecologist).
functional unit of nature/environment. terrestrial ecosystems, aquatic ecosystems. Ecosystem is defined on a community level.
Ecosystem is the biotic community and the physical environment inhabitat by it.
Ecotope- spatial extent of ecosystem(Habitat of community)
Subtypes of Environment
Physical environment- Depicts the physical components of an environment (Mainly non-living components- climate, water bodies, temperature etc.)
Biological environment- Biological components of environment like Flora, Fauna, Human being and micro organism
Cultural environment- Cultural aspects of the environment(generally Man-made) like Church, temple, Gardens etc.
Natural environment- Naturally occurring components of an environment(living + non-living)
Cognitive(Subjective) environment- environment perceived by individuals
Operational environment- all components of an environment that have impact on an individual
4 Sphere of Earth
Lithosphere- rigid outermost Rocky part of earth
Hydrosphere- Total water found on, under and above the earth
(Cryosphere- All water on earth in solid form/frozen)
Atmosphere- layer of gases that surrounds the earth
Biosphere- part of earth where life exists.
Man vs Environment
Charles Darwin(1859, UK naturalist) - life evolved as per the environment.
Friedrich Ratzel(1882-1891, German geographer)- environmental determinists
Ellen Churchill Semple(20th century, American Geographer)- Man is the product of the earth’s environment.
Environmental determinists- human action is controlled by the environment. It is the natural factors that determine the different aspects of human life.
Environment(active agent) → nature of Man(passive agent)
Criticism- Different responses by humans living in the same physical environment.
Ignorance of human impact on the environment.
Environmental possibilism- Vidal de Lablache(French geographer) asserted man as an active agent and environment as a passive element. Later this concept was propounded by French historian Febvre who coined the term possibilism.
As per possibilism theory, the environment provides options, and human(active agent) select an option(but options are limited by environment). Different customs result in different responses by humans living in the same physical environment.
Cultural determinism- culture shapes human nature.
Natural Selection
Natural selection is the process by which species adapt to their environment. The theory of ”evolution by natural selection” was developed by Charles Darwin(British Naturalist) and Alfred Russel Wallace(British Zoologist) independently.
Darwin observed the morphological variations of individuals belonging to the same species at Galapagos Island(Ecuador) and gave the concept of Natural Selection.
Charles Darwin(Father of evolutionary theory) published “On the origin of species by Natural Selection” in 1859.
Natural selection → morphological and genetic changes over generation
Components of natural selection
1. High ratio of young ones 2. Morphological and other variations in organism
3. Struggle to survive 4. Adaptation
Based on Darwin theory of natural selection, Harbet Spencer(British Biologist) coined the term Survival of the fitness(Natural selection + cultural development)
Biological Rules
Gloger’s rule(1833)- Pigmentation ∝ Humidity
Bergmann's rule(1847)- Absolute size ∝ 1/temp (lower surface area to volume ratio)
Allen’s rule(1877)- External body parts of warm blooded animals ∝ 1/temp
Jordan’s rule(19th century)- Fish size and number of vertebrate ∝ 1/temp
Harrison’s rule(1915)- Parasite size ∝ Host size
Hesse’s rule(1937)- Heart size ∝ 1/temp
Foster’s rule(island rule/effect, 1964)- size ∝ resource available in the environment
Rapoport’s rule(1975)- Geographical extent of species ∝ latitude
More species coexist in tropical region than the temperate region
Taxonomy
Taxonomy is the science of hierarchical classification based on evolution of organisms from common Ancestor. The term was coined by Swiss botanist A. P. de Candolle in 1813.
Alpha taxonomy- deciding the species of an organism
Beta taxonomy- deciding the heigher rank of an organism
Evolution Types(Environment Based)
Plasticity- changes in an organism's morphological, physiological, behavioural and phenological traits.
Natural selection- evolution based on adaptation of nature/environment
Artificial selection- evolution based on nature+ human introduced changes(gene insertion)
Isolation- evolution based on non-mixing of Genes because of isolation in population of a species.
Evolution Types(Organism Based)
Convergent evolution- Evolution of common features among different species. Wings- bats, birds, butterflies
Divergent evolution- Evolution of different species from a common ancestor. Dogs and foxes evolved from common ancestor wolves.
Parallel evolution- Evolution of two species independently. Two distinct populations in different geographic regions evolve to have similar attributes because they occupy similar niches in similar ecosystems(similar evolutionary pressure).
Coevolution- Evolution of two distinct population led to interdependence of evolved population(Plant and animal)
Cladogenesis- Evolutionary splitting of a parent species into two distinct species(Two branches)
Anagenesis- Evolution of different species from ancestor species over a long period of time without branching.
Evolution Types(Gene Ecology)
Evolution because of Migration(When a species is shifted to new environment-)
Ecophenes/Ecads(same morphology)- morphological changes, no changes in gene(temporary change). Same morphology as the morphology of the local population of new environment
Ecotype(same type)- changes in gene(Permanent change). Same genes as local population
Ecospecies(same species)- same species living in different environment led to change in genes and morphology(Able to breed and produce fertile offsprings)
Coenospecies- Ecospecies able to breed, but sterile offspring
Comparium- Ecospecies that are not able to breed
Evolution(Genetic Drift)
Genetic Drift(reduces genetic variation)- change in the frequency of an existing gene variant in a population due to random chance
Bottlenecks Effect- Loss of genetic variation when next generation population is lower than previous one
Founder Effect- Loss of genetic variations when only small part of big population established new population(generation)
Speciation
Speciation- Formation of different species because of evolution.
The term speciation was coined by Orator F. Cook(American biologist) in 1906.
Geographic mode of speciation
Allopatric- evolution of new species because of geographical isolation(Mountain) of the same species.
Peripatric- when a small group breaks off from the larger group and forms a new species.
Parapatric- species living in large geographical areas but due to pollution or other factors the environment of few geographical regions will change and cause the change in species.
Sympatric- evolution of new species from a specie living in a same geographical region because of reproductive isolation
Niche
Biotic- living components like tree, human, animal
Abiotic- non living components like soil, water, air
Niche
The functional characteristic of a species in its habitat is referred to as the niche of that species in its habitat.
Habitat → Address of a species
Niche → Profession of a species
Niche is the sum of all the activities and relationships of a species by which it uses the resources in its habitat for the survival and its growth.
Different species in an ecosystem can have the same niche or different niche.
Level of Organization
Population- a group of organisms of the same species, occupying a defined area during a specific time.
Community- populations of different kinds of organisms living together and sharing the same habitat.
An ecosystem is an integrated community plus its physical environment.
Biomes- Biomes are groups of ecosystems that share similar climatic conditions and the same kind of abiotic and biotic factors spread over a large area. The biomes are either terrestrial or aquatic.
Biosphere- All the biomes together make up the biosphere. Biosphere is the entire part of the earth where living things exist. This includes soil, water, light, and air.
Ecozones- Ecozones are the biogeographic division of the Earth’s land surface, based on distributional patterns of terrestrial organisms. Divisions based on the historic and evolutionary distribution of plants and animals.(Only terrestrial part, not aquatic part)
Ecotone
Ecotone is the transition zone between two biomes. Like the transition zone between aquatic biome and terrestrial biome.
Characteristics of Ecotone-
The transition zone can be very narrow or quite wide.
The transition zone has climatic conditions intermediate to the adjacent biome. Hence ecotone is a tension zone where adjacent biome species find a little different climate.
The ecotone has species from both the adjacent biome as well as species that are entirely different from that of the adjoining communities.
Edge effect- Sometimes the number of species and the population density of the species is much greater in ecotone than either adjacent biome. The higher biodiversity in ecotone is called edge effect. The organisms which occur primarily or most abundantly in this zone are known as edge species.
Ecology
Ecological explosion- large increase in the population
Ecological release- increase in population because of loss of limiting factors
Ecological transition(John Bennett)- change in the relationship between human and the physical environment because of environmental changes created by human
Ecological succession- change in a species(community) of an area with respect to the changing environment
- Primary succession- newly formed rocks is colonized by living things
- Secondary succession- recolonization of a disturbed area(soil exist) where disturbance was external factors like fire.
Allogenic(abiotic) vs Autogenic(biotic) succession, Hydrarch(aquatic) vs Xerarch(dry region) succession
Ecological footprint- rate of resources consumption and waste generation rate vs recycling rate of earth (human demand on natural capital)
Ecological productivity- rate of generation of biomass(weight) in an ecosystem expressed in mass per unit volume per unit time.
- Primary productivity- ecological productivity of plants/autotrophs
- Secondary productivity- ecological productivity of animals/heterotrophs
Hexicology- Study of the effects of environment on an organism’s growth and behavior.
Ethology- Scientific and objective study of animal behavior especially under natural conditions
Deep ecology- Complex relationships in which the existence of organisms is dependent on the existence of others within ecosystems.
Autecology(Species ecology)- Study of the interaction of organisms with their environment to explain their distribution and abundance.
Synecology(Community ecology)- Study of the interaction among different species and interaction between community and species. Three types of Synecology
(i) Population ecology, (ii) Gene ecology, (iii)Taxonomic ecology
Species
Pioneer species- first to colonize barren environments or disrupted ecosystems.
Ruderal species- plant species that are first to colonize disturbed lands. Ruderal species typically dominate the disturbed area for a few years, gradually losing the competition to other native species. Disturbance- wildfires, avalanche
Foundation species- Primary producers(plants) of an ecosystem that is the foundation of an ecosystem
Keystone species- Species whose addition or loss to ecosystem led a great change in ecosystem
Indicator species- Species whose presence indicated parameters of an ecosystem
Flagship species- Chosen vulnerable species in ecosystem for which conservation efforts are required
Umbrella species- conserving species led to conservation of other species of an ecosystem
Community
Biocoenosis/Biota- biotic community
Major community- self regulating, self sustaining and independent unit comprising a number of minor communities in it. Ex- forest
Minor community- part of major community and dependent on other communities for its existence. Ex- animals dependent on forest
Pioneer community- first community to appear in a bare area(Primary community). Generally the pioneer community comprises small size species. Being a primary community more tolerant to environmental changes but low biodiversity. Good colonizer but poor competitors
Climax community- final community of an area during ecological succession. Species of different sizes adapted to the environment. Less tolerant to environment changes but high in biodiversity, Poor colonizer but good competitors
Seral Community- A seral community is an intermediate stage of ecological succession advancing towards the climax community
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Social Darwinism- Application of biological concepts of natural selection and survival of the fittest to sociology.
Eugenics, Racism, Imperialism and Fascism are the outcome of social Darwinism.
The origin of social Darwinism can be traced to book "The Descent of Man" written by Charles Darwin in 1871. In this book he claimed the racial supremacy of White race on biological grounds. The book not only support the racial discrimination but also support the gender discrimination as it talk about male supremacy over female again on biological grounds.
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