Ecology Interview Preparation Guide

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Ecology is the field of Biology that studies the relations between living beings and between living beings and the environment.

Biome is a prevailing ecosystem constituted by similar biotic and abiotic factors present in one or more regions of the planet.

Autotrophic beings make organic material by photosynthesis or by chemosynthesis. There are photosynthetic autotrophs, like plants, and chemosynthetic autotrophs, like some bacteria.

Autotrophic beings are those that can produce their own food, i.e., that make organic material from inorganic compounds. Heterotrophic beings are those that need to incorporate organic material to nourish them. Therefore, heterotrophs depend on the production of the autotrophs.

Biosphere is the set of all of the ecosystems of the planet.

Ecosystem is a system composed of biotic and abiotic factors in interaction.

Image Diversity: ecosystem

Abiotic factors are the nonliving elements that constitute a given environment, like light, temperature, minerals, water, gases, atmospheric pressure, etc.

Image Diversity: abiotic factors

Biotic factors are the living beings (plants, animals, and microorganisms) that are part of a given environment.

Image Diversity: biotic factors

Ecological niche is the set of peculiar activities, resources, and strategies that a species explores to survive and reproduce. Habitat is the place where the species lives to explore its ecological niche.

In other words, it can be said that habitat is the "address" of the species and the ecological niche is the "profession" of the species.

Community is the set of populations of living beings that live in the same region and interact with each other.

In Ecology population is a set whose members (living in a given place in a given time) are part of the same species. Community is a set of populations of different species (living in a given place in a given time).

Population is the set of individuals of the same species found in a given place in a given time.

Species is the set of living beings able to cross among themselves generating fertile offspring.

This concept however does not apply to individuals of exclusive asexual reproduction and other definitions have been proposed. For example, "species is a set of living beings that evolve in a common manner all of them considered ancestors of the same type in relation to common descendants".

The major terrestrial biomes are tundras, taigas (or boreal forest), temperate forests, tropical forests, grasslands and deserts.

Tundras have vegetation formed mainly by mosses and lichens. In the fauna the dense furred animals, like caribous, musk oxen and polar bears, and migratory birds are found.

Biomes - Image Diversity: tundras

Taiga, or the boreal forest, is characterized by coniferous trees, pine forests. There are also mosses, lichens, small bushes, and angiosperms. In the taiga many mammals, like moose, wolves, foxes and rodents, migratory birds and great diversity of insects are found.

Biomes - Image Diversity: taigas

In the temperate forest, deciduous trees predominate. Mammals are found in great number, like bears and deers.

Biomes - Image Diversity: temperate forests

Deciduous trees are plants that lose their leaves in a period of the year. In the case of the deciduous of the temperate forest, the fall of the leaves occurs in the autumn. The loss of leaves is a preparation to face the cold months of the winter: roots, stem and branches are more resistant to low temperature and snow than the leaves; without leaves the metabolic rate of the plant is reduced; the decaying fallen leaves help to nourish the soil.

Biomes - Image Diversity: deciduous trees

Tropical rain forests, like the Amazon forest and the Congo forest, are typically located in low latitude, i.e., in the equatorial and tropical zones.

Biomes - Image Diversity: tropical forests

In the vegetation of the tropical forests, broad-leafed evergreen trees predominate. On the top of the trees, epiphytes and lianas grow. Many varieties of pteridophytes can be found in these forests. Regarding the fauna, the abundance, and diversity is also great: there are monkeys, rodents, bats, insectivores, felines, reptiles, aves, amphibians, and invertebrates, mainly insects.

The biodiversity of these ecosystems can be explained by the great availability of the main abiotic factors for photosynthesis. Since these factors are abundant, plants can perform maximum photosynthetic activity, living and reproducing easily. With great amount and diversity of producers (autotrophs), the consumers (heterotrophic animals and microorganisms) also have abundant food and a complex food web emerges creating many different ecological niches to be explored. So it is possible the appearing of varied living beings as well as the existence of large populations.

In tropical forests, tall trees of several species have their crowns forming a superior layer under which diverse other trees and plants develop forming other inferior layers. From the upper layer to the inferior layers the penetration of light lowers gradually and the exposition to wind and rain, the moisture and the temperature vary. Different compositions of abiotic factor condition the prevailing of different vegetation in each layer.

Grasslands are mainly formed of herbaceous (nonwoody) vegetation: grass, bushes, and small trees.

Biomes - Image Diversity: grasslands

The steppe grasslands of North America are called prairies. The grasslands of South America are known as "pampas" (the steppe grassland) and "cerrado" (the savannah grassland).

Grasslands may be classified into steppes and savannahs. In the steppes, the prevailing vegetation is grass, like in the pampas of South America and in the prairies of North America. The fauna is mainly formed by herbivores, like rodents and ungulates. The savannahs present small trees, like for example the Brazilian cerrado or the African savannahs. The fauna is diverse; in the Brazilian cerrado there are animals like emus, lizards, armadillos, jaguars, etc., and many types of insects; the African savannahs are the home of great herbivores and carnivores, like zebras, giraffes, antilopes, lions and leopards.

Biomes - Image Diversity: savannah

The predominant fauna of the desertic ecosystems is formed by reptiles, like lizards and snakes, terrestrial arthropods and small rodents. In these areas plants very adapted to dry climate may be found, like the cactus, that are plants that do not have real leaves and thus lose less water, along with grasses and bushes near places where water is available.

Biomes - Image Diversity: deserts