Q5.27. Which of the following statements about the effects of climate change on phenology is true?
1. Climate-induced changes in phenology are expected, but have yet to be documented.
2. Temperature-cued spring events are occurring later, because winters are longer and cooler.
3. Changes in phenology do not affect reproduction and therefore have no impact on fitness.
4. Changes in timing are more likely when events are cued by temperature, not day length.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".