Brilliant Bats & Co-evolution PDF

Brilliant bats, and examples of co-evolution Let’s look at co-evolution! Bats and insects (predator and prey) Bats and plants (Pollination syndromes) Bats and viruses Predator avoidance Escape Fool Disappear Annoy/confuse Tympanate Moths Some moths have evolved the ability to hear...

Brilliant bats, and examples of co-evolution Let’s look at co-evolution! Bats and insects (predator and prey) Bats and plants (Pollination syndromes) Bats and viruses Predator avoidance Escape Fool Disappear Annoy/confuse Tympanate Moths Some moths have evolved the ability to hear to avoid echolocating bats More than half of the ∼140,000 nocturnal moth species possess ears specialized to detect bat sonar The ability to hear evolved independently 10-12 times in moths Once heard the moths have different options of how to adaptively respond, as they cannot outfly bats Conversely bats have special methods on target tracking to follow the routes of the moths With 1000+ echolocating bat species that means many approaches Being a bat Laryngeal echolocating bats can emit pulses as short as 0.5 milliseconds, with frequencies that typically range from 25 to 150 kHz Bat’s outer ears functions as two receivers with a specialized skin flap, known as the tragus (though not all species have this) The tragus introduces elevation-dependent spectral changes in echoes, which bats can use for vertical localization -Inter-aural differences are used by the bat to estimate the horizontal object location Echolocation calls Being a bat Call types can broadly be broken into two different categories: frequency modulated (FM) signals and constant frequency (CF) signals. FM signals sweep across a broad range of frequencies and are well suited for target localization CF signals are long narrowband tones, and they tend to be used by bats that hunt for fluttering targets in dense vegetation Some species use combinations of both Acoustic cochlea in ears of CF bats Calls aid in tracking targets in cluttered conditions, bats still must contend with masking effects when target echoes are obscured by other sounds Being a bat Along with acoustic interference in reverberant, cluttered habitats, bats must also operate in a cocktail-party-like environment In acoustically complex environments, bats employ a vast array of behavioral strategies to maximize target information and minimize interference In the presence of conspecifics, bats may adjust frequencies of signals or cease calling entirely, to reduce sonar jamming- or deliberately jam other bats Extreme echolocation call frequency in the African hipposiderid, Cleotis percivalis, frequency higher than any animal ever recorded (∼212 kHz)-silent to insects Bats can also eavesdrop on foraging spots  Tympanate Moths Many night-flying insects evolved ultrasound sensitive ears in response to acoustic predation by echolocating bats Noctuid moths are most sensitive to frequencies at 20-40 kHz Moth's ear mechanically tunes up and anticipates the high frequencies used by hunting bats Strategies Some insects have also evolved various evasive flight maneuvers in response to bat signals: Highly stereotyped linear movement away from the bat, demonstrated by Coleopterans (beetles) Erratic flight trajectories in Lepidopterans (butterflies and moths). Praying mantids have a cyclopean ear to detect bat ultrasound and drop to the ground in response to sonar signals Lacewing moths also cease flying and suddenly plummet downward when they detect the hunting echolocation calls of their main predator, Pipistrellus pipistrellus Tiger moths Bertholdia trigona, have developed ultrasonic clicks, which disrupt the bat’s ability to successfully track prey by using echolocation Escape!-Can’t outfly, can out manoeuvre Escape rule 1: maximize radial acceleration Escape rule 2: turn toward the threat Escape rule 3: flee at an intermediate distance Mantis defences Selection for species active when bats are active to be able to hear higher frequencies Confuse! Click to jam or confuse Baffling the bats In 55% of attacks on moths with tails, the bats went after the tails, often missing the body Long spatulate tails have independently evolved four times in saturniid moths Folding the direction Wingtip folds and ripples on saturniid moths create decoy echoes against bat biosonar Acoustic tomography shows that wingtips of some silkmoths act as acoustic decoys The folds and ripples on wingtips act as acoustic retroreflectors of bat calls Forewing decoys evolved multiple times always as alternative to hindwing decoys Trait evolution across the Arsenurinae phylogeny Separate selection of Hindwings and forewings Fooling bats! Selection of different features to avoid attack of body Evolution of multiple different approaches to avoid damaging attacks Independent evolution in many groups But, there are other types of strategy too fool bat Annoy! Generate ultrasound to confuse and jam Hawkmoths starting producing ultrasound around 26 million years ago -20% of moths produce anti-bat sounds, with at least 6 independent origins of sonar-jamming behavior and more than 10 origins of acoustic aposematism (warning of noxious taste). anti-bat ultrasound production in 52 genera, with eight subfamily origins described Novel mimicry rings Purported acoustic mimicry rings of a community of moths in Sumaco, Ecuador (33 species). A UMAP projection shows clusters of moth anti-bat sounds with similar acoustic features.  Disappear Cloaking scales can dramatically reduce detection (by upto 24%) Absorb sound Eat or be eaten When outflying the predator is not possible then other strategies are needed These may involve flying in unexpected directions, reflecting echolocation to be invisible, or fooling the bat with wing shape so the wrong area is attacked Clicking or jamming is also used, an this can include aposematism or confusion Pollination syndromes  Pollination Bat pollination occurs in approximately 250 genera Nectar bats are larger in mass and jaw length in dry habitats than in wet habitats Average jaw length in nectar bat communities is positively correlated with average corolla length of bat-pollinated flowers ‘Three-world’ view concerning the evolution of vertebrate pollinators and their food plants  Of the 28 orders containing bat pollinated families, only eight (29 %) contain taxa pollinated by both groups of bats 18 of 67 families (27 %) with bat- pollinated taxa have representatives in both hemispheres Bat pollination has evolved independently in about 85 % of these families  Bats Diet-1 Pollination (Pollen & Nectar) Economically important species reliant on bats Durian Parkia Baobab Agave Iroko Some species of bat are able to detect flowers, which act like acoustic ‘cats-eyes” Balleri, A, Griffiths, HD, Baker, CJ, Woodbridge, K & Holderied, MW 2012, ‘Analysis of acoustic echoes from a bat-pollinated plant species: insight into strategies for radar and sonar target classification’. Iet radar sonar and navigation, vol 6., pp. 536-544  1.5x body length! Diet and physiology Evolution and selection Convergent evolution in key genes with nectar feeding birds (aldolase B), drives increased respiratory flux 219 candidate positively selected genes (PSGs; p < 0.05) in Glossophaginae, smaller numbers in old world nectivorous bats and nectar feeding birds Synthesis Strong selective pressure shapes every part of a bat This provides some very interesting examples of co- evolution This is manifested at every level, including on a cellular level For pollination more examples of co-evolution and specialism in the New World, however certain ecosystems (dryer systems) are often reliant on bats due to high dispersal capability Questions?