slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
The General Principles of the Theory of Natural Selection PowerPoint Presentation
Download Presentation
The General Principles of the Theory of Natural Selection

Loading in 2 Seconds...

play fullscreen
1 / 15

The General Principles of the Theory of Natural Selection - PowerPoint PPT Presentation


  • 299 Views
  • Uploaded on

The General Principles of the Theory of Natural Selection. 1. There is natural variation in the populations of all organisms. Individual variation in the Grevy’s Zebra ( Equus grevyi) look closely at the patterns of each individual zebra, they are all different .

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'The General Principles of the Theory of Natural Selection' - ryanadan


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide4

Individual variation in the Grevy’s Zebra (Equus grevyi)look closely at the patterns of each individual zebra, they are all different

Check out this cute gluteal tattoo

slide5

Plains Zebra (Equus quagga)

How many differences in color pattern can you find between these two zebras?

slide6

What about the facial patterns in this group? Notice that all are different. If you can see the difference, what do you think the zebras can determine? Yep, everyone is identifiable as a unique individual.

slide7

Plains Zebra

Grevy’s

Zebra

slide9

3. More individuals are born to each generation than can survive- populations are kept at particular levels by natural “checks”- the Malthusian Principle

slide10

4. Certain forms of a character may be better suited for a particular environment or for a certain set of circumstances within that environment. A leopard that hunts using a “sit-and-wait” strategy (dropping down from a tree onto a passing impala) has little need for the speed of a cheetah, but does need powerful muscles and bone structure, especially to carry the prey back up the tree.

slide11

Pepper Moth (Biston betularia)

Classic example of a moth species with two color morphs, each adaptive under a different set of environmental circumstances. The principle predators of this moth are birds, which hunt using visual cues.

slide12

Oopsie! Not such a good idea to be a white moth on a dark tree, such as this one which is covered with coal soot.

slide13

Demoiselle Crane (Anthropoides virgo)

A trait is said to be “adaptive” if it increases the likelihood that the offspring of the individual possessing it will survive.

This is known as reproductive fitness. An individual is said to be “more fit” if it passes more individuals to the next generation. This crane has a single offspring (chick). Generally speaking, if it makes it to the next generation, the fitness value would be calculated as “1”.

slide14

Another concept of “adaptiveness”: a trait which minimizes expended energy or risk and maximizes gain.

This enhances individual survival, which, in turn, enhances reproductive fitness

slide15

The Concept of “Sexual Selection”, a major contribution of Darwin to evolutionary theory

A little tail never hurt anyone

Widowbird (Euplectes progne)