Evolutionary Biology Flycatchers Paper Flashcards
Divergence of male … signals and female … for those signals often maintains … … between closely related, co-occurring species.
sexual, preferences, reproductive boundaries
Contrasting sources of selection, such as … …, can lead to weak divergence or even … of sexual signals in sympatry
interspecific competition, convergence
When signals converge, assortative mating can be maintained if the … … of females diverge in sympatry (… … …; RCD)
mating preferences, reproductive character displacement
… flycatchers (Ficedula hypoleuca) are sympatric with … flycatchers (F. albicollis) on the Baltic island of Oland, where males from both species compete over nestboxes, their songs converge, and the two species occasionally hybridize.
Pied, collared
This study compares song … of male and female pied flycatchers on Oland and in an … population on the Swedish mainland.
discrimination, allopatric
The study shows that … … flycatchers respond similarly to the songs of both species in sympatry and allopatry, while female pied flycatchers express … … against heterospecific songs in … than in …. These results are consistent with … of song discrimination of female pied flycatchers where they co-occur with collared flycatchers, which should maintain species assortative mating despite convergence of male sexual signals.
male pied, stronger discrimination, sympatry, allopatry, RCD
When females choose mates based on their sexual displays, … in these displays is thought to drive the pre-mating reproductive barriers that are a key component of species boundaries
divergence
In … isolated populations, sexual displays typically diverge over time due to a variety of evolutionary forces, including adaptation to different signalling environments, interactions with different suites of heterospecifics, and … runaway processes
geographically, Fisherian
In secondary contact, the process can be completed through further adaptive divergence of male … and/or female … to avoid … matings
signals, preferences, heterospecific
However, secondary contact between closely
related species may … divergence or even promote … in signals through adaptation to a common … or social interactions with one another
limit, convergence, environment
The potential costs of insufficient signal divergence or signal convergence can in theory be reduced if … … themselves become stricter in sympatry either
through … or … divergence
female preferences, learning, genetic
In many temperate songbirds, song is produced by males
during the beginning of the … season, as a … advertisement and sexual display directed at both rival males and sexually receptive females.
breeding, territorial
… in song is typical even across populations of the same species separated by only short geographical distances
Divergence
Rapid and widespread song divergence is thought
to be caused by a variety of factors acting in synergy: adaptation to transmit in different …, variation in
the strength of … selection, cultural mutation, and selection for local ….
habitats, sexual, conformity
Song convergence may arise as a byproduct of selection for … song learning in other contexts, such as female preferences for … song repertoires and benefits of neighbour song … in intraspecific contexts
open, diverse, matching
Selection for … transmission may select for song similarity in sympatry if males from closely related species signal in largely similar habitats
efficient
Interspecific territoriality may constrain divergence or select for similarity between closely related species to facilitate … interactions
competitive
Insufficient song divergence in sympatry has been shown to lead to an increased risk of …, meaning that determining how and why it is resolved can provide much needed insight into the build-up and maintenance of reproductive isolation in songbirds.
hybridisation
Song discrimination is predicted to evolve over time in … populations, meaning that female discrimination against heterospecific songs may arise simply as a byproduct of sufficient time in …
isolated, allopatry
If time in allopatry is insufficient, sympatry itself may promote stricter song discrimination either as a result
of direct selection to avoid heterospecific songs to reduce … pairing, learning to avoid heterospecific songs due to costly … interactions, or a byproduct of other
evolutionary forces, such as ecological ….
mixed, behavioural, displacement
populations of both flycatcher species have co-occurred in central …, for the last few hundred years, and on the Baltic island of …, for the last … years, where they hybridise
Europe, Oland, 60
In allopatry, their songs are …, but pied flycatcher
males in the sympatric population on Oland commonly copy and incorporate collared flycatcher song elements into their songs.
distinct
The convergence in pied flycatcher songs means that songs overall do not … more across species in sympatry than in allopatry
differ
Song copying is associated with an increased risk
of …
hybridisation
Experiments were conducted at … nestbox areas on Oland, … of which are primarily occupied by collared flycatchers and … of which contain mostly breeding pied flycatchers
11, 7, 4
What was used to record the song?
digital audio recorder and condenser microphone
For recordings of pied flycatchers, most (N = 18 of 20) were classified as … song, while two produced so-called “mixed” songs containing … … song elements.
pure, collared flycatcher
Songs were broadcast at pairs of … nestboxes, located no more than 20m apart, during the period in which males and females were arriving at the nestbox site, and before pair …
unoccupied, formation
At each nestbox, a field … was connected to an mp3 player and clipped onto an overhanging branch. In each pair of nestboxes, one mp3 player was loaded with the songs of a single collared flycatcher individual, while the other was loaded with the songs of a single pied flycatcher individual. A wooden carved flycatcher … was affixed on top of each nestbox, matching the song playback, as a target for stimulated males. The activity of any responding birds was recorded through a … detecting video camera that was set up on a bamboo post, roughly one meter from the nestbox, and positioned to capture the nestbox opening and flycatcher dummy. Playbacks were conducted for … continuous hours at each pair of nestboxes. No pair of nestboxes was tested more than once and, when experiments were conducted the same day in the same nestbox area, each pair of nestboxes was out of hearing range of the next closest pair, at least … apart, to minimize the chances that the same individual visited more than one nestbox pair.
speaker, dummy, motion, two, 100m
On a majority of trials, different colors of water-soluble, nontoxic powder paint were piled onto the lower surface of the nestbox opening, marking the white … feathers of any responding individual so that they could be identified individually on the same day.
chest
Around two-thirds of trials were visited by a single
… (N = 55 of 83 trials), around one-third by a single male and a single female (N = 24), only three trials by a single …, and one trial with two males and a single female.
male, female
Most (80%) individuals (N = 76 of 108) responded to only one song playback in a given setup, but … were significantly more likely to express a song choice (N = 27 of 28 … responded to only one playback) than were ….
females, females, males
Across all responses, the most commonly observed behaviors were: (1) … inside the opening of the nestbox (N = 100 of 130 responses), (2) … the nestbox (N = 65), (3) perching on the top of the nestbox (N = 42), and (4) … the dummy mounted on the top of the nestbox (N = 21).
looking, entering, attacking
Males were both significantly more likely to ... the nestbox (N = 56 of 101 responses) and ... the dummy (N = 20) than were females (N = 9 of 29 responses)
enter, attack
The study observed a significant difference in song discrimination between …. Post-hoc tests suggested that … flycatcher males discriminate relatively more strongly in favour of conspecific songs than … flycatcher males
species, collared, pied
The study found no evidence for a … in the responses of pied flycatcher males from sympatry and in those from allopatry with collared flycatchers.
difference
We found a significant difference in female song discrimination across species. Similarly to males, post-hoc tests suggested that … flycatcher females discriminate relatively more strongly in favour of conspecific songs than … flycatcher females.
collared, pied
However, unlike males, we found evidence for an effect of … on the responses of pied flycatcher females. In …, the responses of collared and pied flycatcher females to conspecific songs did not significantly differ. In contrast, the song preferences of … pied flycatcher females were different from both those of sympatric pied flycatcher females and sympatric collared flycatcher females.
allopatry, sympatry, allopatric
Allopatric pied flycatcher females tend to discriminate in
favour of … songs, while both sympatric pied and collared flycatcher females tend to discriminate in favour of … songs
heterospecific, conspecific
The results suggest that secondary contact affects song discrimination of male and female pied flycatchers …
differently
In an allopatric population, neither male nor female pied flycatchers discriminate against … songs, while, in sympatry with closely related collared flycatchers, female pied flycatchers have relatively stronger discrimination against heterospecific songs, despite … of male signals.
heterospecific, convergence
A previous geographical survey of pied flycatcher songs found that they remain highly … from those of collared flycatchers across multiple … populations
distinct, allopatric
… with collared flycatchers provide the most … explanation than geographic variation in pied flycatcher songs in explaining the observations.
interactions, parsimonious
Female pied flycatchers may have a perceptual preference for collared flycatcher songs in allopatry, but learn to discriminate against collared flycatcher songs in sympatry due to … interactions with collared flycatcher males, as has been demonstrated in guppies, swordtails, Drosophila, and damselflies.
negative
Stricter song discrimination could result from divergence in … underlying the perceptual system involved in song recognition. Genetic variation across species underlies discrimination of conspecific song in … flycatchers, suggesting that relatively stronger discrimination in adult female pied flycatchers could in part be underlain by increased divergence at the relevant genetic loci in sympatric populations. Genetic divergence has been demonstrated in captive canaries to underlie breed-level differences in song discrimination, suggesting that evolution of song discrimination loci could, in theory, be possible, within the 50 years of contact
between the species on Oland. However, it is likely that learned aversion would act synergistically with any genetic factors, making these mechanisms difficult to discriminate in practice.
genes, nestling
It is commonly assumed that selection on species recognition should be … in females than males,
because females bear a stronger … cost when they make an inappropriate mate choice. In line with this prediction, species discrimination is often … in females than in males, including for … recognition
stronger, fitness, stricter, song
In the Ficedula flycatchers, complete or near-complete hybrid … should lead to strong … to avoid interspecific pairings in sympatry, which is thought to be stronger in females than in males.
sterility, selection
Heterospecific song convergence is thought to increase the likelihood of … establishment, particularly when the species differ in their relative proportions and/or
competitive ability. As a result, the songs of
males from the less numerous/aggressive species may be under selective pressure to … and, correspondingly, their song discrimination may be selected to ….
territory, converge, weaken
Asymmetries in species recognition have been proposed to align with differences in the relative … of each species and/or their relative … abilities, under the assumption that individuals from the less common or subordinate species are more likely to depend on successful competitive interactions with the other species to establish and maintain territories. Consistent with this hypothesis, in sympatric locations where pied flycatchers are strongly … by more aggressive collared flycatchers, pied flycatcher males both copy and respond to the songs of collared flycatcher males, while collared flycatchers have not been observed to copy pied flycatcher songs and respond weakly to pied flycatcher songs.
proportions, competitive, outnumbered
However, pied flycatchers also copy collared flycatcher songs where their relative proportions are more …. In addition, there is some degree of habitat … on Oland, suggesting a potential relaxation of competitive interactions, and we demonstrate here that they respond strongly to collared flycatcher songs in allopatry.
similar, isolation
Thus, an alternative explanation for the asymmetry in song copying and recognition is that pied flycatchers express more … song perception innately.
In line with this explanation, … pied flycatchers strongly respond to collared flycatcher songs in allopatry, implying that, in the absence of costs to mistaken interbreeding, pied flycatchers do not discriminate against collared flycatcher songs. Only when the costs of weak pre-mating
boundaries are high, such as on Oland where collared flycatcher males strongly outnumber pied flycatcher males and commonly occupy prime breeding locations, do pre-mating boundaries become ….
plastic, female, stronger
Summary of paper:
… character displacement in songs may aid heterospecific male–male interactions, but can entail severe … to females, especially when heterospecific males are more common. … character displacement of female song recognition should help females alleviate the costs associated with … song divergence and may be an especially likely target of … given the general fine tuning of female discrimination relative to that of males.
Convergent, costs, Divergent, weak, selection
