Some insects harvest nectar by chewing through the wall of...

Some insects harvest nectar by chewing through the wall of the structure that holds the nectar. As a result, they obtain a nectar reward, but pollination does not occur. Suppose that you observed a certain bee species obtaining nectar in this way from a particular orchid species. Over time, how might you expect the characteristics of the orchid population to change in response to this bee behavior?

Key Concepts

Coevolution

Coevolution describes how interacting species influence each other’s evolution over time. When certain pollinators exploit a plant’s resources without providing pollination benefits, the plant may evolve counter-adaptations to minimize these detrimental behaviors, potentially leading to an evolutionary arms race between the species.

Natural Selection

This concept refers to the process by which traits that enhance an organism's fitness are favored over others, leading to changes in population characteristics over time. In the context of plant-pollinator interactions, traits that reduce the negative impact of cheating behaviors, such as nectar robbing, may become more frequent because they improve reproductive success.

Floral Morphology

This term encompasses the physical characteristics and structures of flowers. Changes in floral morphology, such as modifications to the shape, size, or thickness of parts of the flower, can evolve in response to pollinator behavior. In cases of nectar robbing, adaptations may evolve to make it harder for non-pollinating visitors to access nectar without triggering pollination mechanisms.

Mutualism and Cheating

Mutualism refers to a cooperative interaction between two species where both benefit, such as the relationship between most flowering plants and their pollinators. Cheating occurs when one partner gains a reward without providing the expected reciprocal service. In the context of nectar robbing, the pollinator cheats by obtaining nectar without pollinating the flower, which can drive the evolution of plant traits designed to discourage such behavior.

Selective Pressure

Selective pressure is any environmental factor that influences the survival and reproductive success of organisms. The behavior of nectar robbers creates a selective pressure on the plant population, favoring individuals that develop traits to prevent exploitation and improve the likelihood of effective pollination.

Transcript

00:01 This is a question about natural selection and the effects that, in this case, bees that are stealing nectar, and those are usually called nectar robbers, but what the effect the nectar robbers can have on the traits of a flower.

00:20 So this boar flower is dutifully making its nectar, hoping to attract pollinators.

00:26 And these bees are coming along and cutting a hole at the base of the flower.

00:31 And stealing the nectar without going down through the mouth of the flower and doing pollination, which, of course, if flowers could want things, that's what the flower would want.

00:43 So the question is asking us, well, okay, this happens that nectar is sometimes stolen by robbers.

00:50 How should flowers evolve in response to nectar robbers? so we can think of these as evolutionary responses to nectar robbers.

01:05 And keep in mind, what has to happen here is that flowers, different plant species, will vary in their flower traits.

01:11 And those that happen to have traits that deter these nectar robbers a little bit better will end up having more offspring.

01:19 So these traits will become more popular in the population over time.

01:23 Well, there are lots of things that could deter nectar robbers.

01:27 So, for example, you could have a thicker base around the nectary where the nectar is made.

01:37 So you can have a thick base, makes it harder to get, for their nectar robbers to get in...

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