Fecundity selection

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Fitness advantage resulting from the preference of traits that increase the number of offspring .

- Fecundity selection

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Natural selection

Differential survival and reproduction of individuals due to differences in phenotype.

Modern biology began in the nineteenth century with Charles Darwin's work on evolution by natural selection.
Aristotle considered whether different forms could have appeared, only the useful ones surviving.
Part of Thomas Malthus's table of population growth in England 1780–1810, from his Essay on the Principle of Population, 6th edition, 1826
Charles Darwin noted that pigeon fanciers had created many kinds of pigeon, such as Tumblers (1, 12), Fantails (13), and Pouters (14) by selective breeding.
Evolutionary developmental biology relates the evolution of form to the precise pattern of gene activity, here gap genes in the fruit fly, during embryonic development.
During the industrial revolution, pollution killed many lichens, leaving tree trunks dark. A dark (melanic) morph of the peppered moth largely replaced the formerly usual light morph (both shown here). Since the moths are subject to predation by birds hunting by sight, the colour change offers better camouflage against the changed background, suggesting natural selection at work.
1: directional selection: a single extreme phenotype favoured. 2, stabilizing selection: intermediate favoured over extremes. 3: disruptive selection: extremes favoured over intermediate. X-axis: phenotypic trait Y-axis: number of organisms Group A: original population Group B: after selection
Different types of selection act at each life cycle stage of a sexually reproducing organism.
The peacock's elaborate plumage is mentioned by Darwin as an example of sexual selection, and is a classic example of Fisherian runaway, driven to its conspicuous size and coloration through mate choice by females over many generations.
Selection in action: resistance to antibiotics grows though the survival of individuals less affected by the antibiotic. Their offspring inherit the resistance.

Other factors affecting reproductive success include sexual selection (now often included in natural selection) and fecundity selection.

Orb-weaver spider

Orb-weaver spiders are members of the spider family Araneidae.

Argiope sp. sitting on the stabilimentum at the center of the web
Spiderlings in the web near where they hatched
Close-up of the cephalothorax on Eriophora sp. (possibly E. heroine or E. pustuosa)
Gasteracantha cancriformis
Araneidae web
Araneidae waiting on its web for prey
Argiope lobata in Southern Spain

The larger size female is typically thought to be selected through fecundity selection, the idea that bigger females can produce more eggs, thus more offspring.

Index of genetics articles

Science of heredity and variation in living organisms.

Blending inheritance leads to the averaging out of every characteristic, which as the engineer Fleeming Jenkin pointed out, makes evolution by natural selection impossible.

Fecundity selection

Survival of the fittest

Phrase that originated from Darwinian evolutionary theory as a way of describing the mechanism of natural selection.

Herbert Spencer coined the phrase "survival of the fittest".

The biological concept of fitness refers to both reproductive success (fecundity selection), as well as survival (viability selection), and is not prescriptive in the specific ways in which organisms can be more "fit" by having phenotypic characteristics that enhance survival and reproduction (which was the meaning that Spencer had in mind).

Wolbachia

Genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes.

Indonesian research minister Mohamad Nasir during a visit to a Wolbachia mosquito lab of the Eliminate Dengue Project.
Adi Utarini, research lead of the Wolbachia trial in Yogyakarta, Indonesia

Wolbachia strains captured from 1988 in southern California still induce a fecundity deficit, but nowadays the fecundity deficit is replaced with a fecundity advantage such that infected Drosophila simulans produces more offspring than the uninfected ones.

Evolution of ageing

So much variability in the lifespans of organisms.

Naked Mole Rat. Picture taken by: Ltshears - Trisha M Shears.
Constant Failure Rate over Time

"The key conceptual insight that allowed Medawar, Williams, and others, to develop the evolutionary theory of aging is based on the notion that the force of natural selection, a measure of how effectively selection acts on survival rate or fecundity as a function of age, declines with progressive age."

Euglossa cordata

Primitively eusocial orchid bee of the American tropics.

Finally, a mother may eat her daughter's eggs to gain more nutrients, increasing her own longevity and fecundity.

Allochronic speciation

Form of speciation (specifically ecological speciation) arising from reproductive isolation that occurs due to a change in breeding time that reduces or eliminates gene flow between two populations of a species.

Breeding seasons of three populations of a species shift over time eventually causing the isolation of their genes from the other populations. This reproductive isolation can lead to speciation.
A three-dimensional space representing speciation with axes representing the factors involved in the process. The temporal dimension indicates allochrony. The ecological axis correlates with adaptation by time (ABT) whereas the mating axis corresponds to isolation by time (IBT). Breeding time create a fourth dimension expressed as asynchrony in breeding as opposed to synchrony. Speciation events are indicated by the varying colored paths that are taken. A: Absent allochrony, only geographic and mate choice cause isolation. B: Starts with geographic separation, mate choice furthers isolation, and is completed by allochrony. C: Starts with mate-choice differentiation followed by allochrony. D: Mating and ecological factors accompany allochrony.
Speciation represented as a continuum of gene flow where m equals the rate of gene exchange. The three primary geographic modes of speciation (allopatric, parapatric, and sympatric) can exist within this continuum, as well as other non-geographic modes.

Studies of salmonid fishes (involving reproductive lifespans, size at adulthood, age, energy storage, the mass of ovaries, egg sizes, number of eggs in a clutch, fecundity, and rates of development) and flowering plants (involving plant size, duration of flowing time, the number of flowers, the number of fruits, the timing of fruiting, and leaf size) have provided strong evidence of IBT leading to ABT as well as studies of yearly allochrony.