Evolutionary Biology Flycatchers Paper

Question 1

Divergence of male … signals and female … for those signals often maintains … … between closely related, co-occurring species.

Answer 1

sexual, preferences, reproductive boundaries

Question 2

Contrasting sources of selection, such as … …, can lead to weak divergence or even … of sexual signals in sympatry

Answer 2

interspecific competition, convergence

Question 3

When signals converge, assortative mating can be maintained if the … … of females diverge in sympatry (… … …; RCD)

Answer 3

mating preferences, reproductive character displacement

Question 4

… 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.

Answer 4

Pied, collared

Question 5

This study compares song … of male and female pied flycatchers on Oland and in an … population on the Swedish mainland.

Answer 5

discrimination, allopatric

Question 6

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.

Answer 6

male pied, stronger discrimination, sympatry, allopatry, RCD

Question 7

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

Answer 7

divergence

Question 8

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

Answer 8

geographically, Fisherian

Question 9

In secondary contact, the process can be completed through further adaptive divergence of male … and/or female … to avoid … matings

Answer 9

signals, preferences, heterospecific

Question 10

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

Answer 10

limit, convergence, environment

Question 11

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

Answer 11

female preferences, learning, genetic

Question 12

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.

Answer 12

breeding, territorial

Question 13

… in song is typical even across populations of the same species separated by only short geographical distances

Answer 13

Divergence

Question 14

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 ….

Answer 14

habitats, sexual, conformity

Question 15

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

Answer 15

open, diverse, matching

Question 16

Selection for … transmission may select for song similarity in sympatry if males from closely related species signal in largely similar habitats

Answer 16

efficient

Question 17

Interspecific territoriality may constrain divergence or select for similarity between closely related species to facilitate … interactions

Answer 17

competitive

Question 18

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.

Answer 18

hybridisation

Question 19

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 …

Answer 19

isolated, allopatry

Question 20

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 ….

Answer 20

mixed, behavioural, displacement

Question 21

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

Answer 21

Europe, Oland, 60

Question 22

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.

Answer 22

distinct

Question 23

The convergence in pied flycatcher songs means that songs overall do not … more across species in sympatry than in allopatry

Answer 23

differ

Question 24

Song copying is associated with an increased risk

of …

Answer 24

hybridisation

Question 25

Experiments were conducted at … nestbox areas on Oland, … of which are primarily occupied by collared flycatchers and … of which contain mostly breeding pied flycatchers

Answer 25

11, 7, 4

Question 26

What was used to record the song?

Answer 26

digital audio recorder and condenser microphone

Question 27

For recordings of pied flycatchers, most (N = 18 of 20) were classified as … song, while two produced so-called “mixed” songs containing … … song elements.

Answer 27

pure, collared flycatcher

Question 28

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 …

Answer 28

unoccupied, formation

Question 29

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.

Answer 29

speaker, dummy, motion, two, 100m

Question 30

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.

Answer 30

chest

Question 31

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.

Answer 31

male, female

Question 32

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 ….

Answer 32

females, females, males

Question 33

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).

Answer 33

looking, entering, attacking

Question 34

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)

Answer 34

enter, attack

Question 35

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

Answer 35

species, collared, pied

Question 36

The study found no evidence for a … in the responses of pied flycatcher males from sympatry and in those from allopatry with collared flycatchers.

Answer 36

difference

Question 37

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.

Answer 37

collared, pied

Question 38

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.

Answer 38

allopatry, sympatry, allopatric

Question 39

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

Answer 39

heterospecific, conspecific

Question 40

The results suggest that secondary contact affects song discrimination of male and female pied flycatchers …

Answer 40

differently

Question 41

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.

Answer 41

heterospecific, convergence

Question 42

A previous geographical survey of pied flycatcher songs found that they remain highly … from those of collared flycatchers across multiple … populations

Answer 42

distinct, allopatric

Question 43

… with collared flycatchers provide the most … explanation than geographic variation in pied flycatcher songs in explaining the observations.

Answer 43

interactions, parsimonious

Question 44

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.

Answer 44

negative

Question 45

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.

Answer 45

genes, nestling

Question 46

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

Answer 46

stronger, fitness, stricter, song

Question 47

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.

Answer 47

sterility, selection

Question 48

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 ….

Answer 48

territory, converge, weaken

Question 49

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.

Answer 49

proportions, competitive, outnumbered

Question 50

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.

Answer 50

similar, isolation

Question 51

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 ….

Answer 51

plastic, female, stronger

Question 52

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.

Answer 52

Convergent, costs, Divergent, weak, selection