Textbook Notes (368,214)
Canada (161,710)
Biology (305)
BIOL 103 (103)
Chapter 49

BOAG CH49.docx

7 Pages
127 Views
Unlock Document

Department
Biology
Course
BIOL 103
Professor
Virginia K Walker
Semester
Winter

Description
BOAG CH. 49 (pg. 1106-1109): SEXUAL REPRODUCTION ASEXUAL REPRODUCTION -occurs when offspring are produced from a single parents, w/o fusion of gametes from 2 parents -offspring are clones of the parent -prevalent in species that live in very stable environments w/ little selection pressure for genetic diversity in a pop'n Advantages: 1. an animal can reproduce even if it's isolated from others of its own species (non- moving or rarely encounters another) 2. can reproduce rapidly (no hassle of finding, attracting, and mating w/ opposite sex) 3. all asexual individuals can produce offspring (w/ sexual reproduction, 2 parents are needed) -efficient way of producing a lot of offspring done by: budding: a portion of the parent organism pinches off to form a new individual -cells from parent undergo mitosis and differentiate into specific types of structures before the new individual breaks away from parents -can have multiple buds forming -each new animal is fully formed but continues to grow -budding throughout an animal's lifetime regeneration: regrowing a complete organism from a small fragment of their body -eg. worms, sea stars -injured limbs are regrown -2 new individuals can be grown if an organism is split -continues through lifetime--> molecular mechanisms responsible for differentiation into a complete animal remain active during entire lifetime --> gene is expressed during early developmental stages, but remains active throughout life Parthenogenesis: development of offspring from an unfertilized egg -eg. some lizards, invertebrates, fish -animals produced this way are usually haploid -some animals can reproduce either sexually or by these means, depending on their situation -eg. Queen bee will store sperm from during mating season: eggs that are fertilized become diploid females, and when sperm runes out, unfertilized eggs become haploid males SEXUAL REPRODUCTION -production of a new individual by the joining of 2 haploid gametes (sperm and ova) -Fertilization: sperm unites w/ ova to create a zygote -as the zygote undergoes cell divisions + develops--> embryo -less straightforward than asexual reproduction and spends much more E -sexual reproduction allows for greater genetic variation through genetic recombination between successive generations -offspring are a combination of parents' genes; not identical to parents -alleles that provide a selective advantage arise independently in members of a pop'n -sexual reproduction provides the opportunity for 2+ beneficial alleles to be inherited by the same offspring, dramatically increasing its chances of success vs if it were to just have either gene by itself -sexual reproduction makes it easier for pop'ns to eliminate harmful alleles Paland and Lynch Provided Evidence that Sexual Reproduction May Promote the Elimination of Harmful Mutations in Populations -costs of sexual reproduction must somehow be outweighed by corresponding benefits -sexual reprod. allows pop'ns to redistribute alleles via crossing over and independent assortment across many generations -offspring are going to have combos of alleles, some good for success and some bad for success -natural selection favours those w/ alleles that provide greater success and ensures that those with less fitness don't live/reproduce to keep their bad genes alive -asexual reproducers can't reassort their genes in this way + more difficult for them to accumulate good genes/eliminate bad genes -->study of water fleas: some pop'ns repro. sexual while others do asexually -studied mitochondrial genes in sexually reprod. and asexually reprod. fleas -both pop'n
More Less

Related notes for BIOL 103

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit