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Why are bovines different genera if they can interbreed?

Why are bovines different genera if they can interbreed?


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Why are bovinae a "subfamily", above Genus, when members can interbreed? Some like the beefalo are fertile, which is the normal defining characteristic of a species. And Genus are groups more distantly related, so by definition they should not be closely related species.


Species are not defined by whether they can interbreed, not even close.

In fact, there is no objective, scientific standard for what defines species, or genera, at all. What is a species is determined by little more than the "feels" of the individual naming it, or the committee approving it.

And the same is true of the entire rest of taxonomic structure. It's not really science, it's just a way of organizing ideas that got popular, and in fact is under constant assault now by somewhat more scientific things like genetic testing. The hierarchy of the taxonomic system changes pretty much daily, and has no official structure or definition at all. Even the number of kingdoms is entirely up in the air.

Getting back to the specifics here, since there is no objective, scientific standard for what is a species or genus, it's no surprise that separate ones can interbreed.

And it's not like bovines are the only ones. There are many other intergeneric hybrids possible, like sheep and goats, wheat and rye, camels and llama, house cats and servals, marine and land iguanas, et cetera.

Perhaps someday there will be objective definitions to establish a truly scientific taxonomy. But for the moment, it's just whatever people in positions of power feel makes sense, at any given moment.

List of Intergeneric hybrids


Different genus doesn't mean that they are very far away genetically, it means that they can be classified at a clear level above species.

Genus are not strict and codified, they give order in the animal world for groups of the nearest affiliation after species… based on: common ancestry, reasonably compact groupings, distinctness (of ecology morphology etc).

There are 143 bovidae in 50 genera, sheep to gazelle to wildebeest. cows are in the subfamily bovinae, made of 9 or 12 genera and three tribes.

They have decided that cows are of three types, buffalo's, bison's and bos/ox, in the tribe bovini, and that there oryx, kudu and bongo antelope are cousins of cows from a different bovinae tribe.

Scientists have agreed that bison can be grouped in a different group, genus, that zebu and cattle. It's logical.

vs vs

They have agreed that indian cows, zebu, from indian aurochs, is in nearly the same as a cow derived from eastern aurochs, compared to the 5 species of buffalo. For example with pigeons, they have decided to group all the species related to the wood pigeon into one group, and the columbidae family actually has 42 genera of pigeons, mostly exotic and tropical ones, and even stuff like dodo's.

https://simple.wikipedia.org/wiki/Bovinae

They make mistakes regarding genus as often as for species, and may have to swap around a species from one genus to another based on genetic evidence, even if two genus have members with parallel ecologies and appearances.

Taxonomists will say "Tragelaphus and Taurotragus genera are sometimes included with bovinae", the groups can be blurred and flexible.

It's a messy job for taxonomists. http://bioweb.uwlax.edu/bio203/s2007/hayes_katy/images/ruminants.bmp

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSWBirAqviIKqUNdGHbxfhZJ9JcK57jU8mYD5iydpV5wFIARCQJ

https://www.researchgate.net/publication/225666813_DNA_barcoding_of_18_species_of_Bovidae

https://ai2-s2-public.s3.amazonaws.com/figures/2017-08-08/9b140afd9d0d3eaf61ac9bde4560f8c9c207e380/9-Figure4-1.png">ShareImprove this answeredited Jul 12 '19 at 12:35answered Jul 12 '19 at 12:14DeltaEnfieldWaidDeltaEnfieldWaid8,01714 silver badges32 bronze badges

Why are bovines different genera if they can interbreed? - Biology

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Difference Between Genus and Species

All living organisms present on the earth are categorized into groups for easier understanding. Taxonomy is a branch of science which deals with the scientific categorization of organisms into separate groups based on the presence and absence of certain characteristics. The characteristics may be physical or genetic. ‘Taxis’ in Greek refers to order and arrangement. Classification of all organisms including plants, animals and microbes according to a set of rules brings in uniformity and simplicity while studying these organisms across the globe. The taxonomic hierarchy consists of

Kingdom – Phylum – Class – Order – Family – Genus – Species.

Common names would have created lot of confusion as every country would have had a separate name for the same organism. The need to bring in standardization in the process of naming gave birth to the binomial naming system both in zoology and botany. This is a scientific naming process adopted all over the world across language barriers. It helps to reduce confusion.

Binomial naming system consists of giving two names to an organism. Just like we have a name and a surname, the organisms are named after their genus and species. These are the lowest two levels in the taxonomic system of naming. The first name is the genus followed by the name of their species. For example Homo sapiens refer to human beings. The word Homo refers to genus and the word sapiens refers to species. Let us understand certain differences between genus and species.

Species is defined as the largest group organisms that can interbreed to produce a fertile offspring. Organisms having similar set of DNA and similar physical and morphological attributes are said to be of the same species. They have the same number of chromosomes and thus possess similar morphological characteristics. The male and female of the same species can interbreed to produce a fertile offspring of the same species.

The name of the species or the specific name/epithet forms the second part of the binomial nomenclature. It is generally written in small letters and italics. Species are basically groups or populations of animals that have a high degree of genetic similarity. There may be many species under the same genus.

‘Genus’ in Greek means ‘race’. It comes below the family and above the species in the taxonomic hierarchy. Many a times it is not possible to identify all organisms up to the level of the species, especially the fossilized and extinct ones. In such case identifying the genus of the organism is enough to label it.

A genus can have many species. Organisms of different species of the same genus cannot produce a fertile offspring if interbred together. Mule is a classic example of this. It is a product of a donkey and a horse which are two different species belonging to the same genus (Equus).

The genus or the generic name precedes the specific name in binomial classification. The first letter is written in capital letters. The generic name is also written in italics and can be abbreviated to the first letter. For example: Homo sapiens or H. sapiens.

To summarize genus and species are the lower most ranks in the taxonomic hierarchy of the scientific naming system.


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Intergeneric Hybrid

An intergeneric hybrid is a cross between plants in two different genera in the same family. They are closely related enough that pollination will produce a hybrid, though the seeds of this hybrid are usually sterile.

The more distant the relationship between the two genera, the greater the difficulty of intergeneric hybridization. Genera that generate intergeneric hybrid are always genetically related members of the same taxonomic tribe. Intergeneric hybridization represents an opportunity to combine genomes from distinctly different plants and to introgress traits not found in the main genus of interest. Many intergeneric hybrids are infertile.

This type of hybridization is more for scientific interest than for any other use.


7 Answers 7

Historically, cow refers to a female, and steer or bull refers to a male. The plurals of these are cows, steers and bulls. The 1896 edition of Webster's Collegiate Dictionary (found on Google books) defines cow as:

  1. The mature female of bovine animals.
  2. The female of certain large mammals, as whales, seals, etc.

If you want to refer to more than one of this kind of animal, and don't want to specify the gender, you call them cattle. Cattle is often treated as an uncountable noun. 1 To specify three of them, you would say three head of cattle.

There is historically not a singular, non-gender-specific word for one head of cattle. Your father and grandfather used cattle as a singular to fill this gap. Other people are now using cow for this, and this usage is common enough to have made it to the dictionaries. I don't know whether it's common enough to be considered correct among farmers, however, or whether it's just us ignorant city-folk who use it.

1 Update: Looking at Google Ngrams and books, I was surprised to find two cattle used instead of two head of cattle relatively often, although two head of cattle is the more common term.

Singular should be bovine, a cow is basically a female bovine, and bull or steer is a male. People started saying cow, I don't know why, in the 20Th century for some reason (I do not know why) and the correct name should be bovine, cattle (Bos Taurus), is just multiple bovines, but bovines works the same way. If you are saying a domestic bovine, then say ox/oxen . Hope this helps. I have general knowledge on "cows"

In Western Australia, in my youth (1960s), people on cattle stations called individual cattle a 'beast', especially when the sex was unknown. I'm not sure how widespread this was/is but WP says it's a known usage in (at least parts of) Australia, New Zealand, Canada and Britain.

In the 1950's and 60's in the county of Angus in Scotland where we had a farm with cattle, the singular of cattle e.g. one far enough away for one not to know its sex was called a 'cattle-beast'. That sounds a bit clumsy but is quite precise, in that it states that the animal being spoken of is bovine but sex is undetermined.

According to the Oxford English Dictionary, cattle is the plural of cow in US English and cow refers to 'the female of any bovine animal'. However, it also mentions that cow can also refer to 'a domestic bovine animal, regardless of sex or age'.

There are no entries in the Oxford English Corpus of cattle being used as a singular noun.

I would say that it is fine to refer to both the male and female as cows, and also that I can see no evidence that cattle can be used as a singular.

What ever happened to 'cain'. In my early dicationaries that was the correct singular non-gender specific of domestic cattle.

Oxford Living Dictionaries (aka Oxford Online Dictionary or ODO) offers as a definition for cow

1.1 (loosely) a domestic bovine animal, regardless of sex or age.

But the same resource answers the vocabulary question What is the word for a cow that doesn't specify its sex?

The truth is that there is no noun in general use that refers equally to a cow or a bull.

Zoologists use two terms. The first is 'ox', which is often restricted to animals of the genus Bos (i.e. the wild cattle - gaur, banteng, yak, aurochs, and kouprey - as well as domestic cattle). In popular use, though, the word 'ox' often refers to a castrated male animal, so that isn't a perfect solution. The second zoological term is 'bovine', which is used as a noun to refer to any animal of the wider group that comprises cattle, buffaloes, and bison. But this would be a strange choice in most general contexts (emphases mine).

And the same source in a blog entry called The peculiar history of cows in the OED says:

. Very rarely [sic] do we stop and think about the fact that cows are not, technically speaking, a species. They’re only the female half.

. In the plural, we can say that they’re cattle (except when cattle is used to mean livestock generally). But the singular is messier. The word ox is one candidate, as it originally meant ‘a cow, a bull’, but now is more often specified to a ‘castrated adult male of this animal.’ Heifer is also sometimes used as a sex-neutral term, though this too is not strictly correct. Some may accuse such a position of pedantry, noting that the use of cow to refer to the species has grown so pervasive as to have changed its meaning, but that doesn’t mean the phrase ‘male cow’ is going to make scientific sense any time soon (emphases mine).

Note that The opinions and other information contained in OxfordWords blog posts and comments do not necessarily reflect the opinions or positions of Oxford University Press.

When I am amongst my rural kin I have learned to call a cow a cow and a bull a bull and not to mix the two.


Materials and Methods

Materials

Estradiol, heparin, Hepes, sodium pyruvate, antibiotics, mineral oil, and tissue culture medium-199 (TCM-199) were purchased from Sigma-Aldrich (St. Louis, MO). Folltropin was purchased from Agtech, Inc. (Manhattan, KS). Fetal calf serum (FCS) was obtained from Hyclone Laboratories, Inc (Logan, UT). Minimum essential medium (MEM) without glutamine was obtained from Life Technologies (Grand Island, NY), and unsupplemented embryo culture medium (simplex optimization medium, KSOM) [ 21] was purchased from Cell and Molecular Technologies Inc. (Phillipsburg, NJ). Modified Tyrode albumin lactate pyruvate (TALP) solutions (Hepes-TALP, SPERM-TALP, and IVF-TALP) were prepared as described by Parrish et al. [ 22]. However, IVF-TALP was modified to contain essentially fatty acid-free BSA (6 mg/ml) instead of fraction V. Frozen domestic bull semen (Jersey bull, n = 2 ejaculates) was acquired from Sire Technology Int. (Springfield, OH). Unless otherwise stated, all other chemicals and supplies were from either Sigma-Aldrich or Fisher Scientific (Orlando, FL). Investigations described herein were approved by the Center for Research of Endangered Wildlife’s Animal Care and Use Committee.

Semen Collection and Cryopreservation

Two male FE oryx (Ogac 1 [4 yr old] and Ogac 2 [8 yr old]) and two male SH oryx (Oda 7 [11 yr old] and Oda 9 [8 yr old]) served as semen donors. Animals were fed diets of alfalfa or grass hay ad libitum and pelleted feed three times/day with continuous access to water and mineral blocks. Anesthesia and semen collection by electroejaculation for the SH oryx were as previously described [ 17, 18]. The FE oryx were immobilized on three separate occasions using a combination of 2.6 mg carfentanil (Wildlife Laboratories Inc., Fort Collins, CO) and 15 mg xylazine (Phoenix Scientific, St. Joseph, MO) by means of a projectile dart. Surgical anesthesia was achieved 4–6 min after darting, and animals were supplemented with 100 mg ketamine (Fort Dodge Animal Health, Fort Dodge, IA) administered intravenously. An endotracheal tube was passed following recumbence as a precaution against regurgitation or apnea. Electroejaculation was performed as previously described [ 17, 18] with a series of stimuli, ranging from 2 to 6 V. An i.v. injection of 20 mg yohimbine (Wildlife Laboratories Inc.) and 250 mg naltrexone (Wildlife Laboratories Inc.) reversed anesthesia, and animal recovery was closely monitored for 24 h. Semen samples were evaluated immediately upon collection for volume and motility. Sperm concentrations were determined using a hemacytometer, and a 5-μl aliquot was fixed in PBS containing 6% (v/v) glutaraldehyde for sperm morphological analysis.

Sperm processing and cryopreservation were conducted as previously described [ 18]. In brief, ejaculates from each oryx were diluted 1:1 with EQ extender prewarmed to 37°C. Tubes containing the diluted semen were placed into a waterbath to which ice was occasionally added allowing samples to cool slowly for 1.5 h. When samples reached ≤8°C, similarly cooled EQ containing 10% (v/v) glycerol was added incrementally to the extended semen, with 20-min equilibration intervals between each addition (25%, 25%, and 50% of volume). After an additional 1 h incubation, 0.5-ml straws were filled with extended semen, sealed, and frozen in a liquid nitrogen dry shipper as previously described [ 18].

Oocyte Collection and In Vitro Maturation

Collection and in vitro maturation of domestic cow oocytes were as previously described [ 23, 24]. Abattoir ovaries were obtained from cows and washed several times with warm sterile saline (0.9% [w/v] NaCl) containing 100 U/ml penicillin-G and 100 μg/ml streptomycin (30–35°C). Cumulus oocyte complexes (COCs) were retrieved by slicing follicles (2–6-mm diameter) with a scalpel blade and then washing the ovaries vigorously in 200 ml of collection medium (TCM-199 with Hanks salts, 10 mM Hepes, 2% [v/v] FCS, 40 U/L heparin, 250 IU/ml penicillin-G, and 250 μg/ml streptomycin). Only COCs having one or more layers of cumulus cells and evenly granulated ooplasm were selected. Groups of 10 COCs were washed several times and placed into 50-μl drops of maturation medium (TCM-199 with Earle salts, 10% [v/v] FCS, 50 μg/ml gentamicin, 0.2 mM sodium pyruvate, 2 μg/ml estradiol, and 20 μg/ml FSH [Folltropin]) covered with mineral oil. COCs were allowed to mature for 22–24 h at 39°C in an atmosphere of 5% CO2 in humidified air.

Sperm Preparation, IVF, and Embryo Culture

Sperm preparation and IVF of oocytes were conducted according to previously described methods [ 22– 24] with some modifications. Straws of semen were thawed and washed by centrifugation through a Percoll gradient (45%/90% [v/v]) at 2000 × g for 20 min. The sperm pellet was collected from the bottom of the tube, diluted with 8 ml of sperm-TALP, and centrifuged at 1000 × g for 5 min. The supernatant was removed and the pellet resuspended in 100 μl of IVF-TALP. Sperm concentration was determined using a Makler counting chamber (Sefi-Medical Instruments, Haifa, Israel).

After maturation, COCs were washed twice in Hepes-TALP, and groups of 30 randomly selected oocytes were transferred into four-well plates containing 600 μl IVF-TALP per well. Each well received 25 μl of the sperm suspension (for a final concentration of 1 × 10 6 motile sperm/ml) and 25 μl of PHE (0.5 mM penicillamine, 0.25 mM hypotaurine, and 25 μM epinephrine in 0.9% [w/v] NaCl). Oocytes and sperm were allowed to coincubate for 8 h at 39°C in an atmosphere of 5% CO2 in humidified air. After coincubation, presumptive zygotes were placed in microcentrifuge tubes containing 250 μl Hepes-TALP, vortexed for 5 min, and washed twice in Hepes-TALP. Half the presumptive zygotes (30/drop) inseminated with each sperm sample were placed into 50-μl drops of embryo culture medium (KSOM) supplemented with 2 mg/ml fatty acid-free BSA, 2.5 μg/ml gentamycin, 1× essential and nonessential amino acids, cultured at 39°C in 5% CO2 in humidified air, and were evaluated for cleavage 48 h after insemination. The remaining presumptive zygotes were pipetted through a small-bore pipette to remove any remaining sperm and cumulus cells, mounted, and placed into fixative (25% [v/v] acetic acid in ethanol, room temperature) for 48–72 h. Presumptive zygotes were then stained with 1% (w/v) orcein in 45% (v/v) acetic acid and examined under a phase-contrast microscope at 200× and 400× magnification. Oocytes were considered penetrated when one or more sperm heads and/or male pronuclei and corresponding sperm tails were observed in the ooplasm.

Sperm Morphology, Motility, and Acrosomal Evaluations

Sperm morphology was evaluated in samples after Percoll gradient washing by placing 15 μl of sperm into 5 μl of fixative (8% [v/v] glutaraldehyde in PBS). After Percoll separation and washing, 50 μl of the sperm suspensions were added to 75-μl drops of IVF media containing 5.2 μl of PHE under oil, and maintained at 39°C in 5% CO2. These drops provided a reservoir of sperm for evaluations over time. Sperm motility and acrosome integrity were evaluated as previously described [ 18]. The percentage of motile spermatozoa and forward progression (scale of 0–5, 0 = no forward movement and 5 = rapid forward movement) were evaluated immediately post-thaw, after Percoll gradient separation, and 1, 2, 3, and 8 h after insemination. At each time point, a sperm motility index (SMI = [percentage motile sperm + (forward progressive motility × 20)] ÷ 2) was determined, and a 10-μl aliquot of sperm was smeared on a slide and allowed to air dry. These slides were evaluated for sperm acrosome integrity by staining them with 20 μl of fluorescein isothiocyanate-conjugated Arachis hypogaea (peanut) agglutinin (0.1 mg/ml in PBS) for 30 min in a dark humidified chamber at 4°C. Slides were rinsed in PBS and air dried before evaluation. A drop of mounting medium (4.5 ml glycerol, 0.5 ml PBS, and 5 mg p-phenylenediamine [Sigma]) was placed under firmly mounted coverslips, and the acrosomal status of 100 spermatozoa/slide was evaluated (×400) using fluorescent microscopy (450–490 nm). Descriptions of oryx acrosomal status have been reported previously [ 18].

Zona-Free IVF

Domestic cow oocytes were collected and matured as described above. After maturation, oocytes were washed twice in Hepes-TALP and then vortexed for 5 min in Hepes-TALP containing hyaluronidase (300 μg/ml Sigma) to remove cumulus cells. After vortexing, oocytes were washed and incubated in 0.1% pronase (w/v) in Hepes-TALP for 5–10 min to remove the zona pellucida. Zona digestion was observed continuously using an inverted microscope. When zonae pellucidae were no longer visible, oocytes were immediately washed twice in Hepes-TALP and placed into IVF medium. Oocytes were allowed to recover for 30 min prior to insemination. Zona-free oocytes were randomly assigned to two groups. One group was inseminated with FE oryx spermatozoa, whereas the second group was inseminated with domestic bull spermatozoa. Presumptive zygotes were fixed 8 h after insemination and evaluated for penetration as described above.

Statistics

Cleavage rate, penetration, polyspermy, mean number of sperm/oocyte, and pronuclei formation were analyzed by least-squares ANOVA using Statview (SAS Institute Inc., Cary, NC). All experiments were replicated three times and percentage data were subjected to arcsine transformation before analysis. Values are expressed as means ± SEM and are considered significant at P ≤ 0.05. Differences between means were evaluated by Fisher protected least significant difference. For cleavage analysis, the microdrop was considered the experimental unit with cleavage being recorded separately for each drop. Individual means (n = 2/species except domestic bull) were pooled for motility and acrosome analysis as an overall species estimation. For evaluation of motility and acrosome status over time, a two-way repeated-measures ANOVA was used. Analyses included the main effects of species and time and the species-by-time interaction.


COLLAGEN RECEPTORS

Collagens are deposited in the extracellular matrix, but they participate in cell-matrix interactions via several receptor families (Heino et al. 2007, 2009 Humphries et al. 2006 Leitinger and Hohenester 2007). They are ligands of integrins, cell-adhesion receptors that lack intrinsic kinase activities. Collagens bind to integrins containing a 㬡 subunit combined with one of the four subunits containing an 㬚 domain (㬑, 㬒, 𻄐, and 𻄑) via GFOGER-like sequences, O being hydroxyproline (Humphries et al. 2006 Heino et al. 2007). There are other recognition sequences in collagens such as KGD in the ectodomain of collagen XVII, which is recognized by 㬕㬡 and αv㬡 integrins but not by the 𠇌lassical” collagen receptors (Heino et al. 2007). Several bioactive fragments resulting from the proteolytic cleavage of collagens are ligands of αv㬣, αv㬥, 㬓㬡, and 㬕㬡 integrins (Ricard-Blum and Ballut 2011).

Collagens I–III are also ligands of the dimeric discoidin receptors DDR1 and DDR2 that possess tyrosine kinase activities (Leitinger and Hohenester 2007). The major DDR2-binding site in collagens I–III is a GVMGFO motif (Heino et al. 2009). The crystal structure of a triple-helical collagen peptide bound to the discoidin domain (DS) of DDR2 has provided insight into the mechanism of DDR activation that may involve structural changes of DDR2 surface loops induced by collagen binding (Carafoli et al. 2009) (PDB ID: 2WUH). The activation may result from the simultaneous binding of both DS domains in the dimer to a single collagen triple helix, or DS domains may bind collagen independently (Carafoli et al. 2009). The soluble extracellular domains of DDR1 and DDR2 regulate collagen deposition in the extracellular matrix by inhibiting fibrillogenesis (Flynn et al. 2010). DDR2 affects mechanical properties of collagen I fibers by reducing their persistence length and their Young’s modulus (Sivakumar and Agarwal 2010).

Collagens bind to glycoprotein VI (GPVI), a member of the paired immunoglobulin-like receptor family, on platelets (Heino et al. 2007), and to the inhibitory leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1, Lebbink et al. 2006). Both receptors recognize the GPO motif in collagens. Ligands of LAIR-1 are fibrillar collagens I, II, and III, and membrane collagens XIII, XVII, and XXIII. Collagens I and III are functional ligands of LAIR-1 and inhibit immune cell activation in vitro. LAIR-1 binds multiple sites on collagens II and III (Lebbink et al. 2009). LAIR-1 and LAIR-2 are high affinity receptors for collagens I and III. They bind to them with higher affinity than GPVI (Lebbink et al. 2006, Lebbink et al. 2008), but three LAIR-1 amino acids central to collagen binding are conserved in GPVI (Brondijk et al. 2010). Fibril-forming collagens and collagen IV are also ligands of Endo180 (urokinase-type plasminogen activator associated protein), a member of the macrophage mannose-receptor family that mediates collagen internalization (Leitinger and Hohenester 2007 Heino et al. 2009). The identification of collagen sequences that bind to receptors has benefited from the Toolkits (overlapping synthetic trimeric peptides encompassing the entire triple-helical domain of human collagens II and III) developed by Farndale et al. (2008).


Why does a firefly light up? Is it a defense mechanism?

Its a chemical reaction in their gut where an enzyme reacts with some chemical, atp and oxygen to produce light. They do this for defensive reasons and for sexual reasons. The more frequently a male firefly emits light the more attractive he is.

This is correct. The chemical is called “Luciferin” and the enzyme that catalyzes the reaction “Luciferase”. I can add that different species flash their lights in different patterns so they can help tell each other apart, and that they flash in a sequence that is kind of unpredictable if you don’t know the code so it helps attract mates but not predators.

How is making yourself easier to see in the dark supposed to help you survive in the firefly's case at least for defense?

Different species have different patterns or sequences of flashing. It is not an individualistic trait.

To add to this, male fireflies fly around emitting their lights, while female fireflies hang out in bushes watching. If a female sees a male she likes, she will emit a flash to signal she is receptive to mating. If you watch fireflies, you will notice the ones flying around are always flashing, and the ones in the bushes will flash only rarely.


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