‘Ope’ape’a: The Hawaiian Hoary Bat

• Overview of the subspecies

• Upcoming Research

• Echolocation and moth auditory sensory evolution

• Ebola update

Morphological Studies Morphological Studies Suggest Relative of Suggest Relative of Mainland Hoary batMainland Hoary bat

Lasiurus cenerius Lasiurus cenerius cenerius (North cenerius (North American)American)

L. c. vittosissimus L. c. vittosissimus (South American)(South American)

L. c. semotus L. c. semotus (Hawaiian)(Hawaiian)

Hawaiian Hoary Forest Species• Mainland species also forest species

-utilizes tree roost in native forest-commonality still remains overtime-Hawaiian hoary could be good indicator species

• Strange findings in lava tube on Mauna Loa

• Variable habitat range-found in wet and dry areas of the island-from sea level to 13,000 ft

• Mean home range (consisting of several disjunct activity centers and the day roost)-males 121 ha-females 5.6ha

Inaccurate population Inaccurate population countscounts

Most current Most current population counts population counts based on sightingsbased on sightings

Difficulties with Difficulties with Anabat II Anabat II

Future intraspecific Future intraspecific echolocation analysisecholocation analysis

The importance of The importance of microphone locationmicrophone location

Mainland hoary’s Mainland hoary’s rather lengthy rather lengthy

migrationmigration

Only terrestrial mammals to Only terrestrial mammals to reach Hawaiireach Hawaii

Hawaii—A great place to study evolutionary trends

Morphological Comparisons between L. c. cinerius and L. c.

semotus

• Character divergence:

-flight

-feeding

-45% decrease in body size

Microchiropteran utilize echolocation during hunting

Potential drawback—May alert prey of impending attack

Researchers find it difficult to quantify information

The Hawaiian archipelago is an ideal place to examine moth

hearing as a bat predation defense

• Only one bat species known to exist on the islands

• L. c. semotus exerted entire predatory selection pressure on the ears of sympatric moths.

L. c. semotus prey L. c. semotus prey preferencespreferences

Endemic vs. adventive mothsEndemic vs. adventive moths

Why is H. euclidias preferred over Why is H. euclidias preferred over similar sized endemic moths?similar sized endemic moths?

Effects of artificial lightingEffects of artificial lighting

Insect nervous system auditory processing center evolution

• Ears have appeared 19 times in the class Insecta

• Fundamentally similar structures

• Common selection pressure (bat predation)

Moth ears—neurologically simple

• Consist of up to four auditory receptors• It has been proposed that the closeness of the

bat as perceived by the moth determines the bimodal defense flight behavior

5 acoustic stages in 5 acoustic stages in foraging echolocation:foraging echolocation:

1.1. SearchSearch

2.2. ApproachApproach

3.3. TrackingTracking

4.4. Terminal Buzz (I)Terminal Buzz (I)

5.5. Terminal Buzz (II)Terminal Buzz (II)

The moth also has certain neurological stages that somewhat

correlate to the approaching bat behavior

Stage #1: The most sensitive Stage #1: The most sensitive receptor, A1receptor, A1

The moth directionally detects with its The moth directionally detects with its most sensitive receptor, A1, a most sensitive receptor, A1, a foraging bat that is echolocating in a foraging bat that is echolocating in a searching mode------searching mode------

responses of A1 evoke controlled directional responses of A1 evoke controlled directional flight away from the bat so that the bat flight away from the bat so that the bat does not have a chance to detect the moth. does not have a chance to detect the moth.

Second defense modeSecond defense mode

Bat echolocating in tracking or terminal Bat echolocating in tracking or terminal buzz modebuzz mode

-As bat approaches target, alters the duration, -As bat approaches target, alters the duration, intensity, frequency, and structure of callsintensity, frequency, and structure of calls

- Acoustical reason for this (avoidance of - Acoustical reason for this (avoidance of pulse-echo overlap)pulse-echo overlap)

A1 and less sensitive A2 receptor A1 and less sensitive A2 receptor activatedactivated

Triggers erratic flight patternTriggers erratic flight pattern

A1 receptors encodes bat calls A1 receptors encodes bat calls as a near bat until 100-200 ms as a near bat until 100-200 ms

before the attackbefore the attack disactivation of interneurons and a disactivation of interneurons and a

premature cessation of near-bat premature cessation of near-bat responses. responses.

-little selection pressure to maintain -little selection pressure to maintain vigorous A1 response for the final ms of a vigorous A1 response for the final ms of a moth’s life?moth’s life?

--may be an adaptive tactic used by the bat may be an adaptive tactic used by the bat to facilitate captured of eared moths to facilitate captured of eared moths

A2 receptor may be vestigial and not used in flight response

May play a role in a different bat defense—sound emission (echo jamming effect

Function of the B cell

• may in fact be vestige of a homologous proprioceptor in thoracical earless moths

• persistence in eared noctuid moths is reflection of low evolutionary cost of simple nervous systems

So if moths evolved ability to So if moths evolved ability to avoid bat predation, shouldn’t avoid bat predation, shouldn’t they eventually lose this they eventually lose this ability when relieved from bat ability when relieved from bat predation pressures?predation pressures?

Four suggested conditions that Four suggested conditions that must be met before phenoypic must be met before phenoypic effects of bat release will occur:effects of bat release will occur:

1.1. Complete isolation from batsComplete isolation from bats

2.2. Absense of alternative uses for earsAbsense of alternative uses for ears

3.3. Genetic isolation from bat-exposed Genetic isolation from bat-exposed conspecificsconspecifics

4.4. Sufficient evolutionary time in bat-Sufficient evolutionary time in bat-released conditionreleased condition

Bats in the news: Ebola resevoirs?

• Scientists have long wondered where the ebola virus hides between outbreaks.

-fast killer, so often covers tracks quickly

-primates die from infection

• Maybe it’s the bats

Researchers have injected bats Researchers have injected bats with the virus and they have with the virus and they have

survived, but only recently have 3 survived, but only recently have 3 fruit bats been found in nature with fruit bats been found in nature with genetic sequences from the virus or genetic sequences from the virus or evidence of an immune response to evidence of an immune response to

it.it.Traces of the virus were found in Traces of the virus were found in

the animals' liver and spleenthe animals' liver and spleen

Maybe it’s the birds…

the outer protein shell of filoviruses, such as

Ebola, have a biochemical structure similar to retroviruses carried by birds, making a common evolutionary origin more likely.

Until more is known public Until more is known public education is important in education is important in preventing the spread of preventing the spread of the diseasethe disease