Female reproductive strategies

Question 1

How do female strategies vary from male strategies?

Answer 1

• Less variance in reproductive output
• More parental investment
• Limited by access to energetic resources

Question 2

What is the main limiting resource for female reproduction?

Answer 2

Food

females need regular and high quality food supply

Question 3

What are the 2 main lines of evidence proving that food is the limiting resource for female reproduction?

Answer 3

1. Provisioned Colobines
   - Females in provisioned primate colonies increase their reproductive output.
   - Shorter inter-birth interval, younger age at 1st reproduction.
2. Amenorrhea (body stops ovulating)
   - Females with a very low % of fat stop cycling. This is because fat reserves support the embryo/ fetus during gestation and during nursing.

Question 4

What factors determine how much food is required for energy levels?

Answer 4

• Basal metabolic rate
• Active metabolism
• Growth rate
• Reproductive effort

Question 5

Describe the energy case study that looked at energy balance and reproductive success in Sanje Mangabeys

Answer 5

-Study subjects: Mizimu group (63-65 Sanje Mangabeys in the Udzungwa mountains.

Urine samples were collected -By collecting urine samples, you can measure moderate changes in energy balance in response to food availability and energy expenditure by measuring the volume of C-peptide which is a by-product of insulin production.

Study showed: -in the wet season fruit is more abundant which is when most babies are being conceived. Females are building up their fat reserves before getting pregnant, conceiving and all though babies are born at a time with low food availability, it’s okay because the females already have fat reserves for milk.

• Reproductive success of females is significantly different depending on whether they conceive at the right time when high quality food is available.
• If females don’t have a high-quality diet in the early gestation period, their babies are 8x more likely to die once born. The early gestation period is the most sensitive part of development in humans and most likely in primates too.

Question 6

What is the core diet for primates?

Answer 6

often fruit, seeds and young leaves.

-Then depending on primate species may include mature leave, insects, flowers/ nectar, sap and sometimes meat.

Question 7

Describe the Jarman-Bell principle

Answer 7

• Small bodies primates have a higher turn-over of food in the gut plus they eat smaller meals with a higher metabolism. As well as if the food is passing through quickly there is reduced time to absorb nutrients.
• High quality food tends to be things like sap and fruit which are high in simple sugars which are the easiest things to digest as it can be absorbed through the wall of the stomach.

-Having a longer gut in larger bodied primates means they have more time to access the nutrients so they can handle lower quality food. This tends to be things like plant foods (grass, plants, bark) The cellulose is very hard to break down and you need the help of good bacteria in the intestine. Like the multichambered stomach of the colobines.

Question 8

What are the main differences between a high and low quality diet?

Answer 8

High quality diets:

• rich in easily digestible energy and protein.
• growth diets.

E.g fruits, seeds and young leaves

Low quality diets

• Low levels of energy and protein.
• Susistence diets
• E.g mature leaves and bark.

Question 9

Describe the general relationship between body size and diet and how understanding this relationship is important for conservation

Answer 9

• smaller bodied species focus on gum, insects and small lizards. (Tarsier is the only fully carnivorous primate because when animal protein is consumed its much easier to break down) Slightly larger it goes onto fruit and small insects, medium bodied focus on fruit, larger you see the incorporation of fruit as well and then only the largest bodied primates focus on just plant based diets.
• In terms of conservation, understanding how primates use the forest in their diet is important because you can get an understanding of the types of plants or areas of the forest that need protecting to ensure the survival and reproductive success of certain species.

Question 10

What differences in diet occur between male and females?

Answer 10

Female primates generally have higher quality diets than males especially in sexually dimorphic species.

However, -When a female is ovulating a female’s, diet may be more similar to an adult’s male compared to when she’s nursing.

Question 11

What primate foods provide which nutrients?

Answer 11

Fleshy fruit = carbohydrates, lipids (fats)

Young leaves and insects = protein

Flowers = carbohydrates (-Flowers are high in water so some species don’t always have to find external sources of water.)

Seeds = protein, lipids

Tree sap = calcium, carbohydrates

Question 12

What nutrients are eaten in greater quantities to a healthy preganancy?

Answer 12

Folic acid for weight gain and palate and notochord development.

Calcium for bone growth and maintenance.

Protein for oxygen transport to the placenta and fetus.

Question 13

Do female Mangabeys prioritise any nutrients during critical periods of the reproductive cycle?

Answer 13

no significant change in time spent feeding, foraging increasing their feeding intake rate.

But they’re spending more time ingesting fatty high quality foods 4-3 months after conception.