Textbook Notes (290,000)
US (110,000)
Harvard (100)
Chapter 3

SCILIVSY 12 Chapter 3: SLS12- Chapter 3


Department
General Education
Course Code
SCILIVSY 12
Professor
Professor Berry
Chapter
3

This preview shows page 1. to view the full 4 pages of the document.
The$determinant$for$which$species'$characteristics$survive$and$
others$become$extinct
§
Woodpecker's$beak$allows$it$to$gather$insects
A$parasite's$structure$allows$it$to$attach$to$and$feed$off$
another$organism
Bettles'$ability$to$dive$into$water$an$gather$food
Great$variations$in$species$have$allowed$plants$and$animals$to$
become$adapted$to$their$environments
§
The$struggle$for$existence$ (Darwin$credits$Thomas$Malthus$for$
contributions)
The$most$advantageous$characteristics$are$preserved$and$passed$
onto$offspring
§
Natural$selection
Natural$disasters
Shifts$in$climate
Availability$of$food$and$shelter
Prey
Although$nature$can$provide$an$abundance$of$food$and$shelter$to$
its$inhabitants,$it$can$also$be$destructive,$causing$a$struggle$for$life
§
Nature$inherently$disallows$the$survival$of$some$organisms
§
Struggle$for$life
Each$successive$generation$of$species$exponentially$increases$its$
population,$growing$the$world$population$on$a$constant$basis
§
Therefore,$each$individual$organism$must$compete$to$
continue$existing,$and$each$individual$organism's$survival$
inherently$threatens$the$survival$of$another
If$each$generation$continues$to$reproduce$in$greater$numbers$than$
the$one$before,$and$the$rate$of$death$remains$the$same,$the$earth$
will$eventually$run$out$of$room$and$will$be$unable$to$support$all$of$
its$inhabitants
§
Limits$of$population$increase
Future$generations$are$both$dependent$on$and$essential$to$the$
perpetuation$of$advantageous$traits$and$the$progress$of$their$race
§
Most$important$is$the$struggle$between$members$of$the$same$
species
§
Survival$does$not$happen$by$chance,$it$is$the$result$of$
advantageous$variations
An$advantageous$variation,$combined$with$successful$reproduction,$
can$result$in$a$change$in$the$species,$creating$subspecies$better$
equipped$to$handle$its$environment
§
Survival$of$Progeny
One$organism$or$group$possessing$an$advantage$over$another$one$
and$beating$it$out$
§
Species$with$larger$populations$usually$have$a$greater$chance$of$
survival
§
Struggles$for$survival$are$dependent$on$others,$whether$those$
struggles$end$up$being$competitive$or$cooperative$in$nature
§
"Malthus’s$theory$provides$a$rationale$for$why$many$species$
become$extinct:$In$the$competition$to$continue$living,$the$traits$that$
allow$species$to$survive$shape$the$descent$of$new$species,$providing$
the$impetus$for$natural$selection."
§
Battle$for$limited$natural$resources
§
Mutually$beneficial$relationships:$planting$a$tree$allowing$plants$
around$it$to$flourish$-- ensures$collective$ survival
§
How$does$survival$occur$in$the$natural$world?
How$are$different$species$created?
Question$3:
Darwin$provides$examples$of$how$introduced$species$often$flourish$to$explain$his$
theory$of$natural$selection$-- claiming$that$those$with$the$most$advantageous$
characteristics$will$survive$and$pass$those$traits$onto$their$offspring.$Species$have$
naturally$adapted$over$time$to$exhibit$qualities$and$characteristics$that$will$help$them$
survive$and$thrive$in$their$environment$and$those$advantageous$variations$get$passed$
onto$the$next$generation,$almost$reshaping$that$species.$For$example,$Darwin$gives$
the$example$of$a$woodpecker,$and$how$its's$beak$is$shaped$so$that$it$can$easily$catch$
insects;$$woodpeckers'$beaks$have$evolved$so$that$they$are$the$optimum$shape$for$
efficiently$catching$its$source$of$nutrition,$$and$will$continue$to$adapt$in$order$to$
survive$changing$environments,$ecosystems,$and$competition.$
Chapter(3
Tuesday,$ September$ 20,$2016
10:02$AM
You're Reading a Preview

Unlock to view full version