4.1 Species, communities, and ecosystems Flashcards
Table on big picture?
What is a species?
A group of organisms that can potentially interbreed and produce fertile offspring
What are fertile offspring?
Those which can in turn interbreed and pass on their genes to another generation.
Explain how members of species may be reproductively isolated
-Members of a species may be reproductively isolated in separate populations due to geographical barriers, behavioral differences, or niche partitioning.
-For instance, populations of black rats (Rattus rattus) found in different parts of the world are reproductively isolated, as their members cannot come together in the same area to mate.
-However, we expect them to be able to mate and produce fertile offspring if their populations are united.
-If they are not able to mate and produce fertile offspring, it may be that speciation has occurred.
-In this case, they may have evolved to the point where they are too genetically different to produce fertile offspring.
Organisms of the same species will be classified into the same ___
Taxa
Species in these pictures
-The two dogs on the left look very different from each other, so you may not expect them to be in the same species, however, they are both members of the genus and species, Canis familiaris, so for both the Great Dane and the Afghan Hound, the scientific names are the same, however their physical traits are somewhat different.
-The wolf on the right is in the same genus as the two domestic dogs on the left, however, it belongs to a different species, Canis lupus .
Describe the relationship between closely-related species
-Normally, these two species do not live in the same ecosystem; they remain reproductively isolated.
-But in zoos, these large cats sometimes are kept together in enclosures.
-Occasionally in nature and more often in captivity, closely associated species can and will interbreed, but their offspring are normally infertile.
What is a gene pool and what group shares the same gene pool?
-A collection of genes (along with their associated allelic forms) found in a population.
-Therefore, all members of a species share a common gene pool and number of chromosomes in their haploid cells.
Describe the chromosomes of a liger (the offspring of a male lion and female tiger)
-A male lion ( Panthera leo ) and a female tiger ( Panthera tigris ), both of which have 38 chromosomes (2n), have produced an offspring called a liger.
-You can see that this creature shares some characteristics with both a lion and a tiger.
Describe the chromosomes of a mule
Another example is the mule, resulting from the interbreeding of a male donkey ( Equus africanus asinus) with 62 chromosomes (2n) and a female horse ( Equus ferus caballus) with 64 chromosomes (2n).
Why are hybrid species, like the mule, often infertile?
-Horses and donkeys have a different number of chromosomes in their cells, which scientists can see from their karyograms.
-This difference in chromosome numbers is why hybrid species, such as the mule, are often infertile.
Why do we find mostly distinct species as opposed to hybrid species in nature?
Whether hybrid animals come from parents with the same number of chromosomes in their gametes or not, they are typically incapable of producing fertile offspring themselves.
What is a population?
A group of organisms of the same species that live in a particular area at the same time.
Groups of populations can live together to form ___
Communities
What is a community?
A group of populations living and interacting in a particular area.
What is an ecosystem?
A community and its abiotic environment.
What are abiotic factors?
Non-living factors, such as pH, salinity, wind speed, type of soil, etc.
What are biotic factors?
Living factors in an ecosystem, such as the plants and animals.
Diagram showing an individual, population, and community
In a pond, two species of frogs feed on insects.
The insects feed on the algae that live in the water.
What constitutes a population in this ecosystem?
All the frogs of one species
What are organic molecules, such as glucose and amino acids, needed for?
Growth, reproduction and movement.
How many modes of nutrition are there by which organic compounds can be obtained?
-2:
-Autotrophic
-Heterotrophic
What are autotrophic organisms?
-Organisms that are capable of making their own complex organic molecules from carbon dioxide and other simple compounds.
-Almost all plants and some other organisms, for example, Cyanobacteria , Dinoflagellata and Euglenida, are capable of autotrophic nutrition.
What are heterotrophic organisms?
Organisms that obtain their organic compounds through feeding on other organisms.
What are heterotrophic organisms?
Organisms that obtain their organic compounds through feeding on other organisms.
What are the 5 kingdoms?
-Bacteria (Archaebacteria and Eubacteria)
-Protoctista
-Fungi
-Plantae
-Animalia
What is the mode of obtaining organic molecules for bacteria?
Some autotrophic and some heterotrophic
What is the mode of obtaining organic molecules for Protoctista?
Some autotrophic and some heterotrophic
What is the mode of obtaining organic molecules for fungi?
Heterotrophic
What is the mode of obtaining organic molecules for plantae?
Mostly autotrophic
What is the mode of obtaining organic molecules for animalia?
Heterotrophic
What are mixotrophs?
-There are some species that can feed both autotrophically and heterotrophically.
-These organisms are known as mixotrophs. Euglena gracilis is such an organism.
-It lives in ponds.
Picture of Euglena gracilis: an organism that is both heterotrophic and autotrophic
Name the mode of nutrition practiced by secondary consumers.
Heterotrophic
What mode of nutrition do producers and consumers use and why?
-When considering a food chain or food web, the producers are always autotrophs and all consumers are heterotrophs.
-This is because producers can make their own organic compounds, while consumers must feed on other living organisms by ingestion to obtain their organic compounds.
How can heterotrophs be grouped?
-According to the way they get their organic molecules from other organisms.
-The most obvious way is by ingesting or eating other organisms.
-But that would pose a problem for those organisms that do not have a mouth, or other anatomical feature, that would allow eating.
Biologists categorize heterotrophs in ___ broad groups.
Three
What are the three broad groups that biologists categorize heterotrophs into?
-Consumers
-Detritivores
-Saprotrophs
Describe how the range of consumers is enormous
-Some organisms, such as elephants, fish, or otters, get carbon compounds by ingestion or eating.
-They consume other living organisms or recently living organisms.
-In the case of an elephant, that could be grass or branches of trees, whereas an otter mainly consumes fish.
-Once ingested, their food is digested.
-Some consumers are much smaller: Paramecium and other unicellular organisms take in their food, usually bacteria or algae, by endocytosis.
-Once inside, their food is digested in food vacuoles using the digestive enzymes from lysosomes.
Parasites as consumers
-Some parasites are considered consumers, for example, the tapeworm, but they do not have a digestive tract.
-Instead of ingesting or eating, they rely on their host to break down food then they absorb the nutrients directly through their skin or cuticle.
Define ingestion
-The taking in of a substance (be it solid or liquid food, medication, toxic substances, or indigestible materials).
-In animals, ingestion takes place through the mouth, but it could occur by any other means to allow entry into the body.
What are consumers?
Organisms that gain nutrients by feeding on other organisms using ingestion or absorption.
What is the difference between ingestion, digestion, and egestion?
Ingestion is a term used for feeding, digestion is the breakdown of food once it has been ingested, and egestion is the waste or undigested material that leaves the body.
How are consumers further defined by what they eat?
-Primary consumers (1º) feed only on autotrophs, these organisms are also known as herbivores.
-Secondary consumers (2º) feed on primary consumers, and tertiary consumers (3º) feed on secondary consumers.
-Organisms that feed solely on other consumers are known as carnivores and can be classified even further by the type of consumer they eat, for example, the giant anteater (Myrmecophaga tridactyla) is considered a carnivore, but more specifically an insectivore, which makes them secondary consumers in the food chain.
Identify the following organism as an autotroph or heterotroph.
If the organism is a heterotroph, identify it as a consumer, detritivore, or saprotroph.
Autotroph
What are decorator crabs and how does this property benefit them?
-Decorator crabs ‘decorate’ their shells with sponges, corals, and even urchins in order to camouflage themselves from predators.
-This benefits the other organism by giving them a mobile place to attach and live.
Picture of lichen growing on a tree branch
Drawing of commensalism (a bird’s nest in a tree)
Picture of a mosquito
An example of parasitism is the relationship between a mosquito and a human.
The mosquito depends on human blood for its nutrition while causing humans itchy bites and in some regions acting as a vector in spreading diseases such as malaria and zika.
Diagram of an example of a simplified version of a nutrient cycle
Picture of a bed of tube worms near the base of a black smoker
Picture of a mesocosm (sealed)
