5/22•If you haven’t sent me your vine please do so immediately

•Vines & presentations•More on hybrids!•Phylogenics of human ancestry•7.1 exit slip back•HW: 7.1 quiz, finish data collection and answer the questions from the human ancestry packet.

Hybrids…The Grey area of speciation

How Do Hybrids Form?

• Offspring resulting from the interbreeding between two species

• This typically happens when a geographical barrier is removed. Naturally or by people.

Why do hybrids occur?

1. Species is a human created concept, nature doesn’t always comply.

2. Pre-zygotic barriers change.– climate change, drought, erosion…

3. MANY natural hybrids exist! Happens where 2 species have common habitat.

4. Some are only because humans put certain animals or plants together.

In Animals!• For a hybrid to be viable, the chromosomes of the

two organisms usually have to be very similar. – i.e. the parent species must be closely related– Same # of chromosomes is important – More important is alleles line up

MULE: Strong and docile it’s a mix of the fragile horse (but easily trainable) and strong willed (but sturdy) donkey

Sterile! chromosomes don’t match up and chromosome number is different.So mules are sterile because horse and donkey chromosomes are too different for viable gametes. But they exist because horse and donkey chromosomes are similar enough to make a viable offspring.

LIGER: Biggest cat due to imprinted genes. Not sterile (19 from dad, 19 from mom) but continued hybridization = break down

Hybrid breakdown is a reproductive failure that appears after a second generation crosses between different species or subspecies. Caused by alleles not lining up.

Why Are There No Cheegers or Cheepoards?

Groler Bear Found due to increasing warmth and habitat change.

Fertile?Seem able to get past second generation. In 2010 one was tested and genetics showed it’s mother was a hybrid.

No Grizzly Pandas :(

Hybrids Taking Over?

• Climate-driven migrations could increase more meet-ups, and more hybrids.

• Could lead to extinction by merger

Hybrids Are VERY Common in Plant History

**humans are diploid = 2n**

Benefits of Polyploidy in Plants

HW due Wednesday!!!•HW:

–7.1 quiz– finish data collection and answer the questions from the human ancestry packet.

•Re-assessment on Tuesday AcLab!

Review7.1 exit•Watch your phrasing, it is SUPER important in Evolution especially…

•Evolution/natural selection/mutation is not purposeful.–Mutations occurred to make longer necks to get food

•Mutations randomly occurred which have the population variation in neck length.

–Natural selection made them adapt•NS occurred because short necks cant get food as well as long nwecks so they are less likely to survive and reproduce. Or in other words long necks end up being more fit since they can reach more food thus breed more often.

–Evolved so they wouldn’t die•Evolved through NS acting on the variation in the population.

•Don’t say the “stronger” survived…unless it’s really that it’s stronger….•Ex: Sloths are not strong but they survive