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The Salmonidae family is the only extant member of the suborder Salmonoidei, and its name literally means 'salmon-like'.
Answer: True
Explanation: The Salmonidae family is indeed the sole extant member of the suborder Salmonoidei, and its name directly translates to 'salmon-like,' reflecting the characteristic morphology of these fish.
Salmonids are primarily warmwater fish, preferring tropical and subtropical waters of the Southern Hemisphere.
Answer: False
Explanation: Salmonids are characterized as coldwater, mid-level predatory fish, predominantly found in the subarctic and cool temperate waters of the Northern Hemisphere, not tropical or subtropical Southern Hemisphere regions.
The Atlantic salmon, Salmo salar, is considered the eponym for the Salmonidae family and order names.
Answer: True
Explanation: The Atlantic salmon, *Salmo salar*, is indeed recognized as the eponym for both the Salmonidae family and the broader order names, with its Latin genus name, *Salmo*, also contributing to this nomenclature.
Salmonids are carnivorous predators that occupy the middle of the food chain, feeding on smaller fish, crustaceans, and aquatic insects.
Answer: True
Explanation: Salmonids are indeed carnivorous predators, positioned in the middle of the food chain, with a diet comprising smaller fish, crustaceans, aquatic insects and larvae, tadpoles, and occasionally the eggs of other fish.
The largest salmonid individuals can reach up to 2 meters (6 feet 7 inches) in length.
Answer: True
Explanation: While some salmonid species are small, the largest individuals within the Salmonidae family are indeed capable of attaining lengths of up to 2 meters (6 feet 7 inches).
Salmonids are considered keystone organisms primarily because they are a major food source for humans.
Answer: False
Explanation: Many salmonid species are designated as keystone organisms due to their critical role in transferring significant biomass from oceanic to inland ecosystems during their mass migrations, thereby supporting a diverse array of other species, rather than solely for their value as a human food source.
What is the literal meaning of the name 'Salmonidae'?
Answer: Salmon-like
Explanation: The name Salmonidae literally translates to 'salmon-like,' indicating the characteristic appearance of these fish.
Which of the following is NOT a common fish type found within the Salmonidae family?
Answer: Pikes
Explanation: The Salmonidae family includes salmon, trout, char, graylings, whitefishes, taimens, and lenoks. Pikes belong to the Esocoidei clade, which is distinct from Salmonoidei within Salmoniformes.
What type of habitat do salmonids typically inhabit?
Answer: Coldwater, subarctic and cool temperate waters of the Northern Hemisphere
Explanation: Salmonids are coldwater mid-level predatory fish that inhabit the subarctic and cool temperate waters of the Northern Hemisphere.
Which species is the eponym of the Salmonidae family and order names?
Answer: Atlantic salmon
Explanation: The Atlantic salmon, *Salmo salar*, is the eponym of the family and order names, with its Latin name, *Salmo*, also becoming the name of its genus.
Which of the following is a distinctive physical characteristic of salmonids?
Answer: Slender bodies with rounded scales and forked tail fins
Explanation: Salmonids possess slender bodies with rounded scales, forked tail fins, pelvic fins positioned far back on their bodies, and an adipose fin towards the rear of their back.
What is the maximum length that the largest adult salmonid individuals can reach?
Answer: 2 meters (6 feet 7 inches)
Explanation: While the smallest salmonid species can be as short as 13 cm (5.1 inches) for adults, the largest individuals are capable of reaching up to 2 meters (6 feet 7 inches) in length.
Why are many salmonid species considered keystone organisms?
Answer: Their mass migration transfers significant biomass, supporting other species.
Explanation: Many salmonid species are considered keystone organisms because their mass migration from oceanic to inland water bodies facilitates a significant transfer of biomass, which supports a wide range of other species.
What is the typical diet of salmonids?
Answer: Small fish, crustaceans, and aquatic insects
Explanation: Salmonids are carnivorous predators whose diet consists of smaller fish, crustaceans, aquatic insects and larvae, tadpoles, and sometimes even the eggs of other fish.
What is the minimum length for the smallest adult salmonid species?
Answer: 5.1 inches (13 cm)
Explanation: The smallest salmonid species can be as short as 13 cm (5.1 inches) for adults.
The three main clades of current salmonids are Coregoninae, Thymallinae, and Salmoninae, which are taxonomically treated as subfamilies.
Answer: True
Explanation: The three primary clades of extant salmonids are indeed Coregoninae, Thymallinae, and Salmoninae, which are formally recognized as subfamilies within the Salmonidae family.
Salmoniformes belong to the superorder Protacanthopterygii, which also includes Esociformes and Osmeriformes.
Answer: True
Explanation: Salmoniformes are indeed classified under the superorder Protacanthopterygii, which also encompasses the closely related orders Esociformes, Osmeriformes, and Argentiniformes.
The Salmonidae family is divided into two subfamilies and approximately 15 genera, containing about 150 species.
Answer: False
Explanation: The Salmonidae family is actually divided into three subfamilies, approximately 10-11 extant genera, and around 200-220 species, rather than two subfamilies, 15 genera, and 150 species.
The Coregoninae subfamily includes the genera Coregonus, Prosopium, and Stenodus.
Answer: True
Explanation: The Coregoninae subfamily correctly includes the genera *Coregonus* (whitefishes), *Prosopium* (round whitefishes), and *Stenodus* (beloribitsa and nelma).
The Thymallinae subfamily contains only one extant genus, Thymallus, which includes 14 species.
Answer: True
Explanation: The Thymallinae subfamily is indeed monotypic, containing only the extant genus *Thymallus* (graylings), which comprises 14 recognized species.
The Salmonini tribe includes the genera Brachymystax and Hucho.
Answer: False
Explanation: The Salmonini tribe includes *Salmo*, *Salvelinus*, and *Salvethymus*. *Brachymystax* and *Hucho* are genera within the Oncorhynchini tribe.
The two extant clades within the order Salmoniformes are Salmonoidei and Esocoidei.
Answer: True
Explanation: Within the order Salmoniformes, the two recognized extant clades are indeed Salmonoidei, which exclusively contains Salmonidae, and Esocoidei, which includes pikes and mudminnows.
Recent phylogenetic studies have led to the re-inclusion of Esocoidei as a suborder of Salmoniformes, after it was initially redefined as a monotypic order including only Salmonidae.
Answer: True
Explanation: Recent phylogenetic research has indeed led to the re-inclusion of Esocoidei as a suborder within Salmoniformes, following an earlier redefinition that had temporarily limited Salmoniformes to a monotypic order containing only Salmonidae.
The genus Salvelinus, which includes char and trout like brook trout, contains 51 species.
Answer: True
Explanation: The genus *Salvelinus*, encompassing char and various trout species such as brook trout and lake trout, is indeed composed of 51 recognized species.
The Oncorhynchini tribe includes the genus Parahucho, which contains 4 species.
Answer: False
Explanation: While the Oncorhynchini tribe does include the genus *Parahucho*, this genus contains only 1 species (*Parahucho perryi*, the Sakhalin taimen), not 4 species.
How many extant genera are recognized within the Salmonidae family?
Answer: 11
Explanation: The Salmonidae family consists of 11 extant genera and over 200 species.
Which of the following is NOT one of the three main clades (subfamilies) that comprise current salmonids?
Answer: Esocoidei
Explanation: Current salmonids are composed of three main clades, taxonomically recognized as subfamilies: Coregoninae, Thymallinae, and Salmoninae. Esocoidei is a separate clade within the order Salmoniformes, not a subfamily of Salmonidae.
What evidence suggests that the three salmonid lineages form a monophyletic group?
Answer: They share a suite of derived traits from a common ancestor.
Explanation: All three salmonid lineages are accepted to share a suite of derived traits, which are characteristics that evolved in their common ancestor and are unique to the group, indicating they form a monophyletic group.
What were the two extant clades within the order Salmoniformes reaffirmed by recent phylogenetic studies?
Answer: Salmonoidei and Esocoidei
Explanation: Recent phylogenetic studies have reaffirmed that the two extant clades within the order Salmoniformes are the Salmonoidei, which contains only Salmonidae, and the Esocoidei, which includes pikes and mudminnows.
Which superorder do Salmoniformes belong to?
Answer: Protacanthopterygii
Explanation: Salmoniformes belong to the superorder Protacanthopterygii, alongside the closely related orders Esociformes, Osmeriformes, and Argentiniformes.
How many species does the genus Coregonus (whitefishes) contain within the Coregoninae subfamily?
Answer: 78 species
Explanation: The Coregoninae subfamily includes *Coregonus* (whitefishes) with 78 species.
Which of the following genera belongs to the Salmonini tribe and contains 51 species?
Answer: Salvelinus
Explanation: The Salmonini tribe includes *Salvelinus* (char and trout like brook trout and lake trout) with 51 species.
Which of the following genera is NOT part of the Oncorhynchini tribe?
Answer: Salmo
Explanation: The Oncorhynchini tribe includes *Brachymystax*, *Hucho*, *Oncorhynchus*, and *Parahucho*. *Salmo* belongs to the Salmonini tribe.
What is the species count for the genus Thymallus (graylings) within the Thymallinae subfamily?
Answer: 14 species
Explanation: The Thymallinae subfamily contains the genus *Thymallus* (graylings), which includes 14 species.
Which of the following orders is NOT listed as closely related to Salmoniformes within the superorder Protacanthopterygii?
Answer: Cypriniformes
Explanation: Salmoniformes belong to the superorder Protacanthopterygii, alongside the closely related orders Esociformes, Osmeriformes, and Argentiniformes. Cypriniformes is not listed as closely related within this superorder.
The temporal range of the Salmonidae family begins in the Early Cenozoic era, specifically the Paleocene epoch.
Answer: False
Explanation: The temporal range for the Salmonidae family begins in the Late Cretaceous period, specifically the Campanian stage, not the Early Cenozoic or Paleocene epoch.
The order Salmoniformes, which includes Salmonidae, first appeared during the Early Jurassic period.
Answer: False
Explanation: The order Salmoniformes, encompassing the Salmonidae family, first emerged during the Santonian and Campanian stages of the Late Cretaceous period, not the Early Jurassic.
The earliest known fossil salmonid, Sivulliusalmo alaskensis, was described in 2025 from the early Maastrichtian-aged Prince Creek Formation in Alaska.
Answer: True
Explanation: The fossil record indicates that *Sivulliusalmo alaskensis*, described in 2025 from the early Maastrichtian-aged Prince Creek Formation in Alaska, represents the earliest known fossil salmonid.
The discovery of Sivulliusalmo in southern, warm-water habitats suggests a recent adaptation of modern salmonids to cool, high-latitude waters.
Answer: False
Explanation: The discovery of *Sivulliusalmo* in northern, cool-water habitats suggests that the preference for cool, high-latitude waters is an ancient and conserved trait among salmonids, rather than a recent adaptation from warm-water environments.
Prior to 2025, the earliest record of salmonids was the Early Eocene-aged Eosalmo driftwoodensis, found in central British Columbia.
Answer: True
Explanation: Before the description of *Sivulliusalmo* in 2025, *Eosalmo driftwoodensis*, an Early Eocene stem-salmonine discovered in central British Columbia, was considered the earliest known fossil record of salmonids.
Eosalmo driftwoodensis is considered important because it represents a fully modern salmonid, lacking any archaic traits.
Answer: False
Explanation: *Eosalmo driftwoodensis* is significant as an archaic salmonid that exhibits traits found in all three modern subfamily lineages, indicating its ancestral position rather than representing a fully modern form.
The split between the Oncorhynchus and Salmo genera is estimated to have occurred around 5 million years ago, during the Pliocene.
Answer: False
Explanation: The divergence between the *Oncorhynchus* and *Salmo* genera is estimated to have occurred much earlier than the Pliocene, potentially as far back as the Early Miocene, approximately 20 million years ago.
Salmon and pike are thought to have diverged from one another during the Cenozoic era.
Answer: False
Explanation: The divergence between salmon and pike is believed to have occurred during the Cretaceous period, predating the Cenozoic era.
Indeterminate remains of Sivulliusalmo were identified from the older Campanian-aged Dinosaur Park Formation of Alberta, in addition to the Prince Creek Formation.
Answer: True
Explanation: Indeterminate fossil remains of *Sivulliusalmo* were indeed discovered in the older Campanian-aged Dinosaur Park Formation of Alberta, supplementing the findings from the early Maastrichtian-aged Prince Creek Formation in Alaska.
After Eosalmo driftwoodensis, trout-like fossils of the Oncorhynchus genus appear in the salmonine fossil record about 15 million years ago.
Answer: False
Explanation: Following *Eosalmo driftwoodensis*, there is a gap in the salmonine fossil record until approximately 7 million years ago (Late Miocene), when trout-like fossils, including *Oncorhynchus* species, emerge.
The presence of Oncorhynchus species in Idaho before the Pliocene indicates that Pacific salmon and trout lineages had already diverged.
Answer: True
Explanation: The discovery of *Oncorhynchus* species inland in Idaho prior to the Pliocene epoch confirms that the Pacific salmon and trout lineages had already undergone divergence by that time.
From which geological period does the temporal range of the Salmonidae family begin?
Answer: Late Cretaceous
Explanation: The temporal range for the Salmonidae family extends from the Late Cretaceous period, specifically the Campanian stage, up to the present day.
When did the order Salmoniformes, which includes Salmonidae, first appear?
Answer: Late Cretaceous
Explanation: The order Salmoniformes, which contains the suborder Salmonoidei and thus the family Salmonidae, first appeared during the Santonian and Campanian stages of the Late Cretaceous period.
When is it thought that salmon and pike diverged from one another?
Answer: Cretaceous period
Explanation: It is thought that salmon and pike diverged from one another during the Cretaceous period, a time of significant evolutionary change.
What was the earliest known fossil salmonid described in 2025?
Answer: Sivulliusalmo alaskensis
Explanation: The earliest known fossil salmonid, *Sivulliusalmo alaskensis*, was described in 2025 from the early Maastrichtian-aged Prince Creek Formation in Alaska.
What does the occurrence of Sivulliusalmo in northern habitats suggest about modern salmonid traits?
Answer: The preference for cool, high-latitude waters is an ancient and conserved trait.
Explanation: The occurrence of *Sivulliusalmo* in these northern habitats suggests that the modern salmonid preference for cool, high-latitude waters is an ancient and conserved trait, indicating a long-standing adaptation to such environments.
Prior to 2025, what was considered the earliest record of salmonids?
Answer: Eosalmo driftwoodensis
Explanation: Prior to the description of *Sivulliusalmo* in 2025, the earliest record of salmonids was the Early Eocene-aged *Eosalmo driftwoodensis*, a stem-salmonine, first described from fossils found at Driftwood Creek in central British Columbia.
Why is Eosalmo driftwoodensis considered an important stage in salmonid evolution?
Answer: It shares traits found in all three modern subfamily lineages.
Explanation: *Eosalmo driftwoodensis* is considered an archaic salmonid and represents an important stage in salmonid evolution because it shares traits found in all three modern subfamily lineages.
When do trout-like fossils of the Oncorhynchus genus appear in the salmonine fossil record after Eosalmo driftwoodensis?
Answer: Approximately 7 million years ago (Late Miocene)
Explanation: After *Eosalmo driftwoodensis*, a gap in the salmonine fossil record exists until about 7 million years ago (mya), in the Late Miocene, when trout-like fossils, including several species of *Oncorhynchus*, appear in the Clarkia Lake beds in Idaho.
Which fossil genus, with 1 species from the Eocene, is listed under the Salmoninae subfamily?
Answer: Eosalmo
Explanation: The fossil genus *Eosalmo*, with 1 species from the Eocene, is listed under the Salmoninae subfamily.
The split between Oncorhynchus (Pacific salmon and trout) and Salmo (Atlantic salmon and European trout) is suggested to have occurred as far back as which period?
Answer: Early Miocene
Explanation: The split between *Oncorhynchus* (Pacific salmon and trout) and *Salmo* (Atlantic salmon and European trout) is suggested to have occurred as far back as the Early Miocene, around 20 million years ago.
Salmonids diverged from other teleost fish no later than 88 million years ago, marked by a whole-genome duplication event.
Answer: True
Explanation: Salmonids indeed diverged from other teleost fish no later than 88 million years ago, a significant evolutionary event characterized by a whole-genome duplication in their ancestral lineage, transforming a diploid ancestor into a tetraploid.
The whole-genome duplication event in ancestral salmonids was the first of its kind in their evolutionary lineage.
Answer: False
Explanation: The whole-genome duplication event specific to ancestral salmonids was not the first, but rather the fourth such event in their evolutionary lineage, following two common to all bony vertebrates and one specific to teleost fishes.
Extant salmonids, such as the rainbow trout, show full tetraploidy with all duplicated protein-coding genes and miRNA sequences still present.
Answer: False
Explanation: Extant salmonids, exemplified by the rainbow trout, exhibit partial tetraploidy, where approximately half of the duplicated protein-coding genes have been deleted, though all miRNA sequences retain full duplication.
Polyploidy could not be confirmed in the fossil Eosalmo driftwoodensis because its genome cannot be sequenced.
Answer: True
Explanation: The confirmation of polyploidy in the fossil *Eosalmo driftwoodensis* is not possible due to the inherent limitations of sequencing ancient genomes, which are typically only extractable from extant species.
Current molecular clock analyses suggest that the whole-genome duplication event was the primary driver of speciation within the Salmonidae group.
Answer: False
Explanation: Current molecular clock analyses indicate that periods of intense climate change, particularly those associated with the last ice ages, and the development of an anadromous lifestyle, were the primary drivers of speciation within the Salmonidae group, rather than the whole-genome duplication event itself.
What genetic event marked the divergence of salmonids from other teleost fish no later than 88 million years ago?
Answer: A whole-genome duplication event
Explanation: Salmonids diverged from the rest of teleost fish no later than 88 million years ago, during the late Cretaceous period, marked by a whole-genome duplication event in the ancestral salmonid.
How many whole-genome duplication events have occurred in the evolutionary lineage of salmonids, including the salmonid-specific event?
Answer: Four
Explanation: The whole-genome duplication event in the ancestral salmonid is the fourth of its kind in their evolutionary lineage, following two common to all bony vertebrates and another specifically in teleost fishes.
What evidence of partial tetraploidy is observed in extant salmonids like the rainbow trout?
Answer: About half of the duplicated protein-coding genes have been deleted, but all miRNA sequences show full duplication.
Explanation: Extant salmonids, including the rainbow trout (*Onchorhynchus mykiss*), show evidence of partial tetraploidy where about half of the duplicated protein-coding genes have been deleted, but all apparent miRNA sequences still show full duplication.
What allowed for a more precise dating of the salmonid whole-genome duplication event at 88 million years ago?
Answer: Advances in calibrated relaxed molecular clock analyses
Explanation: New advances in calibrated relaxed molecular clock analyses have allowed for a more precise dating of the salmonid whole-genome duplication event, placing the latest possible date at 88 million years ago.
According to current molecular clock analyses, what is primarily suggested as the driver of much of the speciation within the Salmonidae group?
Answer: Periods of intense climate change associated with the last ice ages
Explanation: Current molecular clock analyses reveal that much of the Salmonidae group's speciation occurred during periods of intense climate change associated with the last ice ages, particularly in salmonids that developed an anadromous lifestyle.
All salmonids are non-migratory fish, spending their entire lives in the same water body where they were spawned.
Answer: False
Explanation: Contrary to the statement, all salmonids are migratory fish, commencing their lives by spawning in freshwater headstreams and subsequently migrating to larger water bodies as adults.
An anadromous life cycle involves salmonid species migrating exclusively between lakes and rivers for different life stages, without entering saltwater.
Answer: False
Explanation: An anadromous life cycle specifically describes euryhaline salmonid species that migrate to the sea or brackish estuaries as adults and return to freshwater streams for reproduction. Migration exclusively between lakes and rivers is characteristic of a potamodromous life cycle.
What type of migratory behavior describes freshwater salmonids that migrate exclusively between lakes and rivers?
Answer: Potamodromous
Explanation: Potamodromous refers to freshwater salmonids that migrate exclusively between lakes and rivers for different stages of their life cycle, without venturing into saltwater environments.
What is an anadromous life cycle for salmonids?
Answer: Migrating to the sea as adults and returning to freshwater for reproduction.
Explanation: An anadromous life cycle describes salmonid species that migrate to the sea or brackish estuaries as adults and return to the upper freshwater streams specifically for reproduction.
In the hybrid crossbreeding table for Salmonidae, the symbol 'X' indicates survivability of offspring.
Answer: False
Explanation: In the hybrid crossbreeding table for Salmonidae, the symbol 'X' denotes fatality, signifying that the hybrid offspring did not survive, whereas 'O' indicates survivability.
Crossbreeding a female Salvelinus fontinalis (brook trout) with a male Salmo trutta (brown trout) results in survivability.
Answer: False
Explanation: According to the hybrid crossbreeding table, the crossbreeding of a female *Salvelinus fontinalis* (brook trout) with a male *Salmo trutta* (brown trout) results in fatality, not survivability.
A female Oncorhynchus mykiss (rainbow trout) can successfully crossbreed with a male Salmo salar (Atlantic Salmon) resulting in viable offspring.
Answer: False
Explanation: The hybrid crossbreeding table indicates that a cross between a female *Oncorhynchus mykiss* (rainbow trout) and a male *Salmo salar* (Atlantic Salmon) results in fatality, meaning viable offspring are not produced.
Crossbreeding a female Oncorhynchus nerka (Sockeye salmon) with a male Oncorhynchus gorbuscha (pink salmon) results in survivability.
Answer: True
Explanation: The hybrid crossbreeding table confirms that crossbreeding a female *Oncorhynchus nerka* (Sockeye salmon) with a male *Oncorhynchus gorbuscha* (pink salmon) results in survivability of the offspring.
Crossbreeding a female Oncorhynchus keta (chum salmon) with a male Oncorhynchus tshawytscha (chinook salmon) results in survivability.
Answer: False
Explanation: The hybrid crossbreeding table indicates that crossbreeding a female *Oncorhynchus keta* (chum salmon) with a male *Oncorhynchus tshawytscha* (chinook salmon) results in fatality, meaning the offspring do not survive.
A female Salmo trutta (brown trout) can successfully crossbreed with a male Salvelinus leucomaenis (white-spotted char) to produce viable offspring.
Answer: True
Explanation: The hybrid crossbreeding table confirms that a female *Salmo trutta* (brown trout) can successfully crossbreed with a male *Salvelinus leucomaenis* (white-spotted char), resulting in viable offspring.
What is the outcome of crossbreeding a female Salvelinus leucomaenis (white-spotted char) with a male Oncorhynchus mykiss (rainbow trout)?
Answer: Fatality
Explanation: When a female *Salvelinus leucomaenis* (white-spotted char) is crossbred with a male *Oncorhynchus mykiss* (rainbow trout), the outcome is fatality, indicated by 'X' in the crossbreeding table.
What does the symbol 'O' indicate in the hybrid crossbreeding table for Salmonidae?
Answer: Survivability
Explanation: In the hybrid crossbreeding table for Salmonidae, the symbol 'O' indicates survivability, meaning that the hybrid crossbreeding combination resulted in offspring that survived.
Which of the following crossbreeding combinations results in survivability?
Answer: Female Oncorhynchus nerka x Male Oncorhynchus gorbuscha
Explanation: Crossbreeding a female *Oncorhynchus nerka* (Sockeye salmon) with a male *Oncorhynchus gorbuscha* (pink salmon) results in survivability, as indicated by 'O' in the hybrid crossbreeding table.
What is the outcome when a female Oncorhynchus tshawytscha (chinook salmon) is crossbred with a male Oncorhynchus kisutsh (coho salmon)?
Answer: Survivability
Explanation: Crossbreeding a female *Oncorhynchus tshawytscha* (chinook salmon) with a male *Oncorhynchus kisutsh* (coho salmon) results in survivability, indicated by 'O' in the hybrid crossbreeding table.