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WHAT IS THE DIFFERENCE BETWEEN A POPULATION AND A SPECIES?
HHarmful AAdaptive NNo Value
Harmful – These types of mutations are detrimental to the organism Either causing it to be less well adapted for its environment, or by causing a basic life function of the animal to function deficiently or not at all
TAKE A MINUTE… Write a brief list of how the albino organisms color mutation is detrimental to that organism’s survival in the wild.
Adaptive – These types of mutations cause the organism to gain some advantage that increases its ability to survive and reproduce successfully
Adaptive Examples: The ability to utilize another food source Disease immunity or resistance Makes the organism more competitive
Examples: Disease immunity or resistance
Mutations can make the organism more competitive
TAKE A MINUTES… Write down a list of at few adaptations that the Giraffe posses that increase its fitness within its environments
No Value – These types of mutations do nothing to either harm the organism or to make them more fit
Mutations assist a species because they cause a variety of variations to exist within that species. Adaptive mutations increase the fitness of a species by providing increased variation
Recurrent mutation – a mutation for a trait that is genetically different from either parent, but is already present in the population
Novel Mutation – a mutation that results in a trait that is not already present in the population
COMPETITION Conflict that arises between individuals or groups in the process of acquiring limited resources
COMPETITION OCCURS BECAUSE OF…. Limiting Resource Any factor (usually a nutrient) within an ecosystem that is in finite quantity and that is required by individuals in that ecosystem for survival
TYPES OF COMPETITION Interspecific - competition between different species Intraspecific – competition within the same species
2 BIOLOGICAL IMPERATIVES 1. Survive 2. Reproduce An organism is FIT if it accomplishes these 2 goals in that order. In fact once an organisms has accomplished both goals that organism will often expire soon for a variety of different reasons
FITNESS “ The relative contribution an individual makes to the gene pool to the next generation” Fitness describes how successful an organism is at accomplishing the 2 biological imperatives. Cambell, Biology
TO CLARIFY… A niche is what an organism does in its community, its habitat is where it lives
2 types Fundamental niche – the resources (biotic and abiotic) that are theoretically available to an organism Realized niche – the resources (biotic and abiotic) that are actually utilized by a given population (Campbell, Biology)
COMPETITIVE EXCLUSION PRINCIPAL “Two species with similar needs for the same limiting resources cannot coexist in the same place” –Campbell, Biology
DARWIN’S OBSERVATIONS 1.If all offspring were able to reproduce successfully populations size would exponentially increase over a few generations 2.In natures populations sizes are relatively stable 3.Limited resources exist in all environments 4.Individuals within the same species have a variety of unique and distinct traits (every individual is different) 5. Many of these variations can be passed on to successive generations
WHAT THIS MEANS… Competition results when more offspring are produced then can survive because resources are limited Offspring that posses more beneficial characteristics are more likely to survive and pass on their genes Because more fit individuals survive most often populations will shift over time to accumulate more beneficial characteristics
This is called….
NOTE Adaptations are not static as environments change so do the characteristics of a population. The best combination of traits changes over time
Note: species do not develop a trait to cope with an element in their environment rather a pool of traits (range of variation) exist within a given population and those that are best adapted survive more frequently and reproduce more successfully.
ALSO NOTE Artificial selection – human modification of species (ex. Selective breeding)
NOTE… Only traits that already exist in a population can be selected for Every adaptation is also a compromise Every adaptation has to be based on a preexisting element of the organism There cannot be a permanently perfect organism
The drive to reproduce can be strong enough in an organism to trump that organism’s drive for survival INTRASPECIFIC NATURAL SELECTION…
A feature possessed by a single sex that increases reproductive fitness (generally in vertebrates)…
IMPORTANT Reproductive fitness can (but doesn’t have to) detract significantly from the environmental fitness of an individual ie. The Peacock …
Please EAT ME!! My big dumb tail feathers make me easy to SEE! And easier to catch!!!
NOTE Sexual secondary characteristic can assist the animal in survival such as a deer’s antlers, but it is often the females that determine the fitness of a Sexual dimorphism
ASEXUAL REPRODUCTION “the creation of new individual's whose genes all come from one parents without the fusion of egg and sperm.” -Campbell Biology Essentially Cloning the Parent
ASEXUAL REPRODUCTION Organisms are well adapted to stable environments cloning maintains the “best combination for the current situation” Less of a chance to introduce detrimental traits into the gene pool No need to find or compete for mates (saves time and energy and can reproduce in isolation) Can produce a large amount of offspring in a short amount of time
Asexual reproduction is best suited to stable environments in which individuals are already well adapted to survive This is because the “best traits” are identically copied into each successive generation ASEXUAL REPRODUCTION
SEXUAL REPRODUCTION “the creation of Offspring by the fusion of haploid gametes to form a zygote, which is diploid.” -Campbell Biology
SEXUAL REPRODUCTION Adds more variety to the population so as a whole the population is better situated to survive and prosper in rapidly changing or new environment Best in new or rapidly changing environment
The Red Queen in “Alice in Wonder Land” had to run at full speed just to stay in the same place. This means that “a species must continually evolve to survive in a world full of other evolving species” –the science of ecology
One example are diseases. A cloned (or asexually reproduced) population is highly susceptible to being wiped out by a contagion. Predator prey relationships are another example
ADAPTIVE RADIATION This process of modification over time to fill a variety of niches is
TYPES OF NATURAL SELECTION …
This type of selection encourages the average or status quo combination of traits. It happens in environments where there is little change occurring STABILIZING SELECTION
DIRECTIONAL SELECTION This type of selection favors a specific combination of traits that were relatively rare in the original population It happens in environments where there is great change occurring or is a species is moving into a new environment
DIVERSIFYING SELECTION This type of selection favors traits on either end of the spectrum but not the middle It happens in environments where there is change but the new factors favor multiple variations, this often happens in a divergence of species
CONVERGENT EVOLUTION When unrelated groups have analogous but nonhomologous features (wings in birds and butterflies, fins in squids and seals), the process is called convergent evolution (sometimes parallel evolution) - similar needs produce similar structures, even if they're based on different architecture. Both support the concepts of evolutionary change by selection.
Due to similar selection pressures that are consistent over long periods of time, unrelated organisms (or distantly related ones) acquire similar traits to deal with those similar pressures.
CONVERGENT EVOLUTION ANATOMY HOMOLOGOUS STRUCTURES ANALOGOUS STRUCTURES Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
PUT ANOTHER WAY… IIt is “the emergence of numerous species from a common ancestor introduced into a new environment, presenting a diversity of new opportunities and problems” – Campbell, Biology
This happens in instances when there exist unrealized opportunities in a new environment. Over time once rare characteristics are emphasized and beneficial. This s divergent or directional selection depending on the circumstance
DIVERGENT EVOLUTION Traits with similar internal structure are called homologous traits When homologous features become used for different purposes - are no longer analogous - the process is called divergent evolution, the splitting of a family tree in different directions. analogous