Mimicry is a fascinating phenomenon in the animal kingdom where one species evolves to resemble another, often unrelated, species for survival advantages. One of the most intriguing examples of mimicry in nature is how some species of moths have evolved to mimic hummingbirds.
What is mimicry?
Mimicry refers to the evolutionary adaptation where one species, the mimic, resembles another species, the model, to gain some fitness advantage. This resemblance can be in appearance, behavior, sound, scent, or a combination of attributes. There are several types of mimicry:
- Batesian mimicry – The mimic is harmless but resembles a harmful or unpalatable species to avoid predation. For example, some non-venomous snakes mimic venomous coral snakes.
- Müllerian mimicry – Two or more harmful species resemble each other to mutually reduce predation risk. Many bees and wasps exhibit Müllerian mimicry.
- Aggressive mimicry – The mimic resembles a harmless species only to attack prey. Anglerfish lure prey by mimicking small fish.
- Vavilovian mimicry – Weeds evolve to mimic crops through unintentional human selection.
Mimics can resemble models very closely or only partially. Imperfect mimics retain enough resemblance to gain some advantage. Mimicry evolves when natural selection favors mutations and adaptations that fortuitously generate similarities.
Examples of mimics
Mimicry is widespread in nature and includes diverse taxa:
- Many palatable butterflies and moths mimic the color patterns of unpalatable species for Batesian mimicry.
- Viceroy butterflies resemble toxic monarchs.
- Some fly and bee species mimic wasps for protection.
- Non-venomous milk snake, kingsnake, and shovelnose snakes mimic venomous coral snakes.
- Many orchids mimic female insects to attract pollinators.
- Cleaner fish mimic poisonous species to approach and eat parasites on larger fish.
- Cuckoos lay eggs mimicking host bird’s eggs to avoid detection.
- In aggressive mimicry, bolas spiders lure moth prey by mimicking moth pheromones.
Mimicry provides fitness benefits like avoidance of predators, parasites, and interspecies competition. It facilitates mating, hunting, pollination, nesting, social integration, and other critical activities.
Moth mimicry of hummingbirds
A fascinating example of mimicry occurs between moths and hummingbirds in the Americas. Certain Sphingidae (hawk moth) species have evolved wing markings, shapes, flight patterns, and behaviors that mimic hummingbirds. This allows the moths to avoid predation and approach nectar sources.
Examples of moth-hummingbird mimicry
Specific cases of moths mimicking hummingbirds include:
- The clearwing moth (Hemaris thysbe) resembles a bumblebee-like hummingbird in size, shape, and flight.
- The hummingbird clearwing moth (Hemaris diffinis) is a near perfect mimic with its furry body and iridescent wings.
- The hummingbird hawk-moth (Macroglossum stellatarum) is widespread across Eurasia and Africa and mimics Old World hummingbirds.
- The horned sphingid (Ceratomia amyntor) mimics the horned hermit hummingbird.
- The ruby-throated hummingbird has multiple hawk moth mimics.
These moths have abdomens and wings shaped like a hummingbird’s body. Their flight patterns also resemble hummingbirds – they can hover in place and fly backwards.
How do moths mimic hummingbirds?
Moth-hummingbird mimicry has evolved through natural selection acting on variation and heritable traits over time. Key adaptations enable the mimicry:
Wing shape and flight
– Long, narrow forewings give an elongated silhouette matching a hummingbird’s body shape.
– Hindwings are small like a hummingbird’s tail.
– Their flight muscles allow hovering and instant acceleration like hummingbirds.
Coloration
– Iridescent wings and body reflect light similarly to hummingbird feathers.
– Disruptive patterns obscure moth outlines and enhance the illusion.
Behavior
– They extend a long proboscis to feed on nectar from flowers just like hummingbirds.
– Many moths even lick or vibrate their proboscis while feeding to imitate hummingbirds.
– Their flight paths from flower to flower resemble foraging hummingbirds.
Why do moths mimic hummingbirds?
Moth-hummingbird mimicry provides several key advantages that increase the moths’ survival and reproduction:
Evasion of predators
– Mimicking hummingbirds allows moths to escape many visual predators like birds, lizards, and frogs that avoid prey the colors of harmful species.
Access to nectar sources
– Moths that mimic hummingbirds can more easily approach flowers adapted for bird pollination. The flowers do not recognize them as threats.
Thermoregulation and energy conservation
– Mimicking hummingbird flight patterns lets moths exploit flower clusters efficiently while minimizing energy expenditure.
– Iridescent scaled wings reflect sunlight keeping moths warm similar to hummingbird feathers.
Defense against parasites
– Mimicking hummingbird beak and feeding actions may help deter parasites. Hummingbirds have better defenses than moths.
Evidence supporting moth-hummingbird mimicry
Researchers have gathered extensive evidence that these resemblances are true evolutionary adaptations for mimicry rather than just coincidences:
- There are many moth and hummingbird species involved in these mimicry complexes across the Americas.
- The resemblances are very detailed including similarities in wing shape, iridescent plumage, feeding behaviors, and flight patterns.
- Modeling shows the wing shape evolution in moths matches hummingbird morphology very closely.
- Sounds generated by moth wingbeats match hummingbird sounds.
- Feeding on a flower, people could not distinguish a moth from a hummingbird in video.
- Flowers visited by moths were also visited by similar regional hummingbirds.
- Related moth species lacking strong resemblance are attacked more by predators.
Researchers propose these mimicry complexes evolved incrementally through a step-wise process via intermediate forms. This evolution was facilitated by the moths’ and hummingbirds’ shared nectar-feeding niche.
Differences between moth and hummingbird mimics
Despite their similarities, some differences remain between moth mimics and hummingbirds:
- Moth mimics are nocturnal whereas hummingbirds are diurnal.
- Hummingbirds have much higher metabolisms and energy needs.
- Hummingbird wings connect to the shoulder while moth wings connect to the abdomen.
- Hummingbirds are vertebrates while moths are invertebrates.
- Moth antennae remain visible despite the mimicry.
- Moth mimics are incapable of sustained high-speed flight unlike hummingbirds.
The mimicry relates mostly to visual cues rather than complete functional resemblance. The moths do not emulate all hummingbird behaviors and capabilities. This enables the mimicry to be successful using fairly simple adaptations.
Significance of moth-hummingbird mimicry
The mimicry between moths and hummingbirds has several ecological and evolutionary implications:
- It expands pollination networks as the moths access hummingbird-adapted flowers.
- Predators must adapt to avoid unprofitable prey.
- It demonstrates the power of natural selection to produce complex adaptations.
- The mimicry may enable speciation into new moth and hummingbird species.
- It shows evolutionary convergence where unrelated species evolve similar traits.
This phenomenon remains an area of active research in evolutionary biology. Scientists continue documenting new examples of moth and hummingbird species involved in mimicry complexes. Ongoing studies aim to reveal more about how the adaptations evolved genetically and physiologically. Analyses of the mimicry’s ecological effects also continue, such as modeling the expanded pollination networks.
Mimicry by other insects
Beyond moths, many other insects also mimic hummingbirds:
- Some hemipteran bugs mimic hummingbirds to evade predators and access flowers.
- Hawkmoth-like flower flies in the genus Spilomyia engage in Batesian mimicry of hummingbirds.
- Some bees and syrphid flies in the Americas resemble hummingbirds.
- Skipper butterflies in the hedylid subfamily mimic hummingbird characteristics.
Convergent evolution has led multiple insect lineages to hit upon similar strategies of mimicking hummingbird traits for their mutual benefit. Beyond hummingbirds, insects mimic many other species too. For example, there are over 10,000 species of hover flies that mimic stinging wasps and bees.
Conclusion
In conclusion, moth mimicry of hummingbirds provides an instructive example of how evolution produces adaptations through natural selection. By incrementally acquiring traits that resemble hummingbirds in shape, coloration, and behavior, various moth species gain survival and reproductive advantages. This mimicry complex highlights nature’s ingenuity and the importance of species interactions. Ongoing research aims to unravel further details of its origins and ecology. Beyond fascinating science, moth-hummingbird mimicry reveals creativity in evolution and how diverse organisms are interconnected.
